Preliminary Studies of a Platelet Function Disorder in Simmental Cattle Gene P. Searcy, David Sheridan and Karen A. Dobson
ABSTRACT
comme anormale. Des plaquettes de bovin dans un systieme d'aggregation A bleeding disorder due to abnor- avec du sang entier n'ont demontre que mal platelet function occurs in tres peu d'aggregation en reponse a Simmental cattle. Whole blood from l'epinephine et 'a l'acide arachidonique. these animals underwent good clot L'aggregation avec un plasma riche en retraction. Platelet aggregation in plaquettes fut negligable en reponse 'a response to adenosine diphosphate l'ADP, le collagene et la thrombine. Le (ADP) and collagen in a whole blood relachement de granules denses de aggregation system was markedly serobonine marquee provenant des impaired. Normal bovine platelets in a plaquettes d'une des vaches affectes fut whole blood aggregation system similaire La celui d'un bovin avec des showed very little aggregation in plaquettes normales. ['electrophorese response to epinephrine and arachi- de la glycoproteine de la membrane donic acid. Aggregation in platelet- plaquettaire d'une vache affectee n'a rich plasma was negligible in response demontre aucune anormalite quantitato ADP, collagen and thrombin. tive. Ces trouvailles rev'elent des Dense granule release of radiolabelled similarites et des differences dans la serotonin from the platelets of one thrombopathie de la fonction plaquetaffected cow was similar to that of taire du Simmental lorsque comparee La normal bovine platelets. Platelet la thrombasthenie de Glanzmann chez membrane glycoprotein electrophore- l'humain et la thrombopathie du Basset sis with the platelets of one affected Hound. (Traduit par Dr Anne Provencher). cow revealed no quantitative abnormalities. These findings reveal similarINTRODUCTION ities and differences in thrombopathic Simmental platelet function when A familial hemorrhagic disorder has compared to human Glanzmann's been detected in Simmental cattle thrombasthenia and Basset Hound (1,2). Over the past decade eight thrombopathia. Simmental cattle have been presented to the Western College of Veterinary Medicine with a history of prolonged RESUME hemorrhage. Bleeding Simmental cattle have also been reported in Ohio Une coagulopathie due 'a un defaut (1) and Kansas (2). de fonction des plaquettes est decrit The common manifestations of this chez le bovin de race Simmental. Du disorder are spontaneous epistaxis, sang entier provenant de ces animaux hematomas and hemorrhage followpresente une formation du caillot ing injury or procedures such as normale. L'aggregation avec plaquet- tattooing. Hematology including taire en reponse a I'ADP et au platelet numbers and morphology, collagene sur un systeme d'aggrega- prothrombin, partial thromboplastin tion avec du sang entier fut notee and clotting times are normal (3).
Kociba has reported impaired platelet function in Simmental cattle with a history of intermittent bleeding. Affected animals had impaired platelet aggregation and glass bead retention. Platelet adenosine diphosphate (ADP) adenosine triphosphate (ATP) and serotonin were normal (1). The purpose of this report is to describe additional platelet function studies in thrombopathic Simmental cattle. MATERIALS AND METHODS CLOT RETRACTION
Tubes of clotted blood were placed in a 37°C incubator for 1 h and clot retraction was compared to that observed with bovine samples submitted to the clinical chemistry laboratory Western College of Veterinary Medicine. PLATELET AGGREGATION
Platelet aggregation using a variety of agonists was carried out on seven Simmental cattle with a history of bleeding. Normal cattle used as controls were of various ages and breeds including Simmental cattle. Blood was drawn into plastic 50 mL centrifuge tubes containing 3.8 g/dL sodium citrate to yield a final blood to anticoagulant ratio of 9/ 1. Platelets were counted with an electronic counter (Coulter Model S+4, Coulter Electronics Inc., Hialeah, Florida) and blood smears were stained using an automatic slide stainer (Hema-Tek, Miles Scientific, Naperville, Illinois). Whole blood platelet aggregation was performed using a Chronolog
Department of Veterinary Pathology (Searcy, Dobson) and Department of Medicine (Sheridan), University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO. This work was supported by the Saskatchewan Agricultural Research Fund, the Canadian Simmental Association and the Dean's Medical Research Council Fund, Western College of Veterinary Medicine. Submitted October 23, 1989.
394
Can J Vet Res 1990; 54: 394-396
whole blood aggro-meter, Model 500 (Chrono-log Corporation, Havertown, Pennsylvania). A 500 ,uL whole blood sample was diluted with 500 1AL of isotonic saline in a 1 mL plastic cuvette containing a siliconized stir bar, then placed in the aggro-meter heating block for mixing and warming to 370C for 5 min. Upon insertion of the impedance electrode, the calibration and the gain controls were used to set the recorder at 5 ohms. After the addition of an agonist, the change in impedance or aggregation curve was recorded at a paper speed of 2.5 cm/ min. The final concentration of agonists in whole blood was as follows: ADP 10 ,imol and collagen 5 ,ug/ mL (Chrono-log Corporation, Havertown, Pennsylvania), arachidonic acid 50 gAg/ mL and epinephrine 1 x 10-5 mol (Bio-Data Corporation, Hatboro, Pennsylvania). Platelet-rich plasma (PRP) aggregation was performed using the Chronolog aggro-meter, model 500. Platelet-rich plasma was prepared by centrifugation of blood at 100 g for 20 min at room temperature. The supernatant was then transferred to a clean plastic tube. The citrated blood was then recentrifuged at 1500 g for 10 min and the platelet-poor plasma (PPP) used to adjust the PRP to a platelet count of 300 x 109/ L for aggregation assay. The following agonists were employed at final concentration in PRP as follows: ADP 10 ,imol, collagen 5 ,ug/mL and thrombin 0.5 units/ mL (Data-Fi, Baxter-Canlab, Edmonton, Alberta). SEROTONIN RELEASE
Labelled (14C)-serotonin was used as a marker to measure release of platelet dense granule constituents as described by Sheridan et al (4). The following agonists were employed at final concentrations of PRP as follows: ADP 1 x 10-5 mol/L and collagen 100 mg/ L (Sigma Diagnos-
tics, St. Louis, Missouri). PLATELET MEMBRANE GLYCOPROTEIN ELECTROPHORESIS
Platelet-rich plasma from an affected Simmental cow and a normal cow was sent to Drs. David Phillips and Israel Charro at the Gladstone Foundation, University of San Francisco, San Francisco, California for platelet glycoprotein electrophoresis.
RESULTS
secretion of constituents which attract more platelets to aggregate with Blood from bleeding Simmental adherent platelets to form a platelet cattle had advanced clot retraction, plug (5). Platelet aggregation follows a series similar to that of normal cattle, at 1 h of events within the platelets resulting of incubation. Thrombopathic platelets failed to in exposure of receptors for fibrinogen aggregate in response to all agonists in and other adhesive proteins. The whole blood and platelet-rich plasma fibrinogen molecule has multiple (Table I). Although there appeared to recognition sites for platelet receptors be a minor response to thrombin by and thus may serve to link adjacent the thrombopathic platelets it was platelets (6,7). The platelet membrane assumed to be insignificant when glycoproteins which bind fibrinogen compared to the response of normal have been extensively studied in platelets. Normal cattle failed to humans. They are two molecules aggregate in response to arachidonic designated glycoproteins (GP) Ilb and Illa which traverse the platelet acid and epinephrine. Release of '4C-serotonin by throm- membrane and are held as a complex bopathic Simmental platelets from by calcium. There are approximately one cow was comparable to the release 50,000 GP Ilb-Illa complexes per obtained with normal bovine platelets human platelet which takes it the most abundant platelet surface protein (6). (Table II). Inherited bleeding disorders have Electrophoretic studies of major platelet glycoproteins failed to reveal been described which are associated any differences between a normal cow with impaired in vitro platelet aggreand an affected Simmental cow. gation. Glanzmann's thrombasthenia occurs in humans with failure of in vitro fibrinogen binding and aggregation due to abnormal platelet memDISCUSSION brane fibrinogen binding proteins, i.e. Platelets are essential contributors GP Ilb-IlIa complexes. A thrombopato the early stages of hemostasis. thia occurs in some Basset Hound dog Vascular injury with exposure of families characterized by failure of in underlying collagen results in platelet vitro fibrinogen binding and aggregaadhesion. Adhesion is mediated by tion due to abnormal fibrinogen Von Willebrand protein, a large receptor availability with no quantitamultimer located within and beneath tive abnormalities in Ilb-Illa comendothelial cells and within platelets. plexes (8). At this point it would appear that It attaches to specific receptors on the platelet membrane and to collagen the bleeding disorder in Simmental thus effecting adhesion. Adhesed cattle has comparable and contrasting platelets undergo activation with features to Glanzmann's thrombasthe-
TABLE I. Platelet aggregation responses in normal and thrombopathic Simmental cattle Whole blood platelet Aggregation (ohms)
Normal N = 25
Thrombopathic
25 ± 6a 25 + 3 I ±3 0
0 0
N=6
N=2
21 +2 11 +1 30 11
0 0.9 ±0.7 2.5 +1.5
N=7
Agonists: ADP
Collagen Arachidonic acid Epinephrine Platelet rich plasma Platelet aggregation (ohms) Agonists: ADP
Collagen Thrombin aMean ± standard deviation
ND ND
ND = Not done
395
Basset Hound thrombopathia is an autosomal recessive disorder characterized by failure of platelet aggregation in response to ADP and collagen. Clot 14C Serotonin release retraction is normal in thrombopathic (% of maximum release)a Normal Thrombopathic Basset Hound dogs and Simmental Agonist cow cow cattle. In contrast to bleeding SimmenCollagen 100 100 tal cattle however thrombopathic ADP 77 18 Basset Hound platelets aggregated in None ND 10 response to thrombin and had impaired aMaximum release was determined by the dense granule secretion of 14Cagonist which yielded the highest number of serotonin. Basset Hound thrombopacounts thic platelets exhibited normal shape ND = Not done change in response to various stimuli and had normal ultrastructural appearnia and the Basset Hound thrombopa- ance (8). Similar studies are indicated thia. Most patients with Glanzmann's on platelets from bleeding Simmental thrombasthenia either lack, or show a cattle. modified clot retraction whereas as Stimulation of platelets with thromnoted in this study and by Kociba the bin or ADP causes an increase in blood from bleeding Simmental cattle intracellular ionized calcium which is undergoes good clot retraction (1). a prerequisite for the secretory and The failure of in vitro aggregation in aggegregatory responses of platelets. response to ADP, collagen and Studies of intracellular calcium thrombin is similar in Glanzmann's responses in thrombopathic Basset disease and thrombopathic Simmen- Hound platelets by Catalfamo and tal cattle. The failure of normal bovine coworkers (8) suggests that such platelets to aggregate in response to responses are impaired, resulting in arachidonic acid and epinephrine has failure of expression of fibrinogen been reported by Meyers (9). Glanz- binding receptors on the platelet mann's patients' platelets have normal surface. Recently Patterson et al (12) dense granule secretion as was true of have shown that thrombopathic the platelets from one bleeding Basset Hound platelets, despite failure Simmental cow (10). Most children to aggregate, are capable of binding with Glanzmann's thrombasthenia fibrinogen. Based on this finding they have electrophoretically demonstrable speculate that the defect in platelet abnormalities in the Ilb-Illa complex function must lie within intracellular (10). Recently however the aggrega- signalling mechanisms which occur tion defect observed with Glanz- subsequent to fibrinogen-receptor mann's thrombasthenia has been interaction. associated with both quantitative and These studies as well as those qualitative alterations in the GP Ilb- previously reported on Simmental Illa complex ( 11). No quantitative cattle demonstrate that the platelet abnormalities of GP Ilb-Illa were abnormality that occurs in these revealed by platelet electrophoresis in animals is unique, when compared to one affected Simmental cow. This other species. Further characterizadoes not preclude an amino acid tion of this abnormality will hopefully substitution at a strategic location in precisely define the platelet function one of the glycoproteins, and fibrino- defect and may allow us to develop an gen binding studies are indicated. assay to detect the carrier state. TABLE II. Serotonin release in citrated platelet-rich plasma from one normal cow and one thrombopathic Simmental cow
396
ACKNOWLEDGMENTS The technical assistance of Dennis Olexson is gratefully acknowledged. Thanks are also due to Dr. Marion Jackson for reading the manuscript and Sandra Mayes for typing the manuscript.
REFERENCES 1. KOCIBA GJ. Partial characterization of a hemostatic defect in Simmental cattle. Vet Clin Pathol 1980; 9: 46-47. 2. LEIPOLD H, MOORE W. Bovine thrombopathia. Listed by Dodds WJ in First Registry of Animal Models of Thrombosis and Hemorrhagic Diseases. ILAR News 1977; 21: A14. 3. SEARCY GP, PETRIE L. Clinical and laboratory findings of a bleeding disorder in Simmental cattle. Can Vet J 1990; 31: 101103. 4. SHERIDAN D, CARTER C, KELTON JG. A diagnostic test for heparin-induced thrombocytopenia. Blood 1986; 67: 27-30. 5. COLLER BS. Disorders of platelets. In: Ratnoff OP, Forbes CD, eds. Disorders of Hemostasis. Montreal: Grune & Stratton, Inc., 1984: 73-176. 6. PHILLIPS DR, CHARO IF, PARISE LV, FITZGERALD LA. The platelet membrane glycoprotein complex. Blood 1988; 71: 831-843. 7. MARGUERIE GA, PLOW EF. The fibrinogen-dependent pathway of platelet aggregation. Ann NY Acad Sci 1983; 408: 556-566. 8. CATALFAMO JL, RAYMOND SL, WHITE JG, DODDS JW. Defective platelet-fibrinogen interaction in hereditary canine thrombopathia. Blood 1986; 67: 1568-1577. 9. MEYERS KM. Pathobiology of animal platelets. Adv Vet Sci Comp Med 1985; 30: 131-165. 10. RAO AK, HOLMSEN H. Congenital disorders of platelet function. Semin Hematol 1986; 23: 102-118. 11. FITZGERALD LA, CHEDIAK J, JENNINGS LK, STROTHER SV, PHILLIPS DR. Identification of molecular variants of Glanzmann's thrombasthenia. Blood 1985; 66: 289a. (Abstr). 12. PATTERSON WA, ESTRY DW, SCHWARTZ KA, BORCHERT RD, BELL TG. Absent platelet aggregation with normal fibrinogen binding in Bassett Hound hereditary thrombopathy. Thromb Haemost 1989; 101 1-1015.
ABSTRACT
comme anormale. Des plaquettes de bovin dans un systieme d'aggregation A bleeding disorder due to abnor- avec du sang entier n'ont demontre que mal platelet function occurs in tres peu d'aggregation en reponse a Simmental cattle. Whole blood from l'epinephine et 'a l'acide arachidonique. these animals underwent good clot L'aggregation avec un plasma riche en retraction. Platelet aggregation in plaquettes fut negligable en reponse 'a response to adenosine diphosphate l'ADP, le collagene et la thrombine. Le (ADP) and collagen in a whole blood relachement de granules denses de aggregation system was markedly serobonine marquee provenant des impaired. Normal bovine platelets in a plaquettes d'une des vaches affectes fut whole blood aggregation system similaire La celui d'un bovin avec des showed very little aggregation in plaquettes normales. ['electrophorese response to epinephrine and arachi- de la glycoproteine de la membrane donic acid. Aggregation in platelet- plaquettaire d'une vache affectee n'a rich plasma was negligible in response demontre aucune anormalite quantitato ADP, collagen and thrombin. tive. Ces trouvailles rev'elent des Dense granule release of radiolabelled similarites et des differences dans la serotonin from the platelets of one thrombopathie de la fonction plaquetaffected cow was similar to that of taire du Simmental lorsque comparee La normal bovine platelets. Platelet la thrombasthenie de Glanzmann chez membrane glycoprotein electrophore- l'humain et la thrombopathie du Basset sis with the platelets of one affected Hound. (Traduit par Dr Anne Provencher). cow revealed no quantitative abnormalities. These findings reveal similarINTRODUCTION ities and differences in thrombopathic Simmental platelet function when A familial hemorrhagic disorder has compared to human Glanzmann's been detected in Simmental cattle thrombasthenia and Basset Hound (1,2). Over the past decade eight thrombopathia. Simmental cattle have been presented to the Western College of Veterinary Medicine with a history of prolonged RESUME hemorrhage. Bleeding Simmental cattle have also been reported in Ohio Une coagulopathie due 'a un defaut (1) and Kansas (2). de fonction des plaquettes est decrit The common manifestations of this chez le bovin de race Simmental. Du disorder are spontaneous epistaxis, sang entier provenant de ces animaux hematomas and hemorrhage followpresente une formation du caillot ing injury or procedures such as normale. L'aggregation avec plaquet- tattooing. Hematology including taire en reponse a I'ADP et au platelet numbers and morphology, collagene sur un systeme d'aggrega- prothrombin, partial thromboplastin tion avec du sang entier fut notee and clotting times are normal (3).
Kociba has reported impaired platelet function in Simmental cattle with a history of intermittent bleeding. Affected animals had impaired platelet aggregation and glass bead retention. Platelet adenosine diphosphate (ADP) adenosine triphosphate (ATP) and serotonin were normal (1). The purpose of this report is to describe additional platelet function studies in thrombopathic Simmental cattle. MATERIALS AND METHODS CLOT RETRACTION
Tubes of clotted blood were placed in a 37°C incubator for 1 h and clot retraction was compared to that observed with bovine samples submitted to the clinical chemistry laboratory Western College of Veterinary Medicine. PLATELET AGGREGATION
Platelet aggregation using a variety of agonists was carried out on seven Simmental cattle with a history of bleeding. Normal cattle used as controls were of various ages and breeds including Simmental cattle. Blood was drawn into plastic 50 mL centrifuge tubes containing 3.8 g/dL sodium citrate to yield a final blood to anticoagulant ratio of 9/ 1. Platelets were counted with an electronic counter (Coulter Model S+4, Coulter Electronics Inc., Hialeah, Florida) and blood smears were stained using an automatic slide stainer (Hema-Tek, Miles Scientific, Naperville, Illinois). Whole blood platelet aggregation was performed using a Chronolog
Department of Veterinary Pathology (Searcy, Dobson) and Department of Medicine (Sheridan), University of Saskatchewan, Saskatoon, Saskatchewan S7N OWO. This work was supported by the Saskatchewan Agricultural Research Fund, the Canadian Simmental Association and the Dean's Medical Research Council Fund, Western College of Veterinary Medicine. Submitted October 23, 1989.
394
Can J Vet Res 1990; 54: 394-396
whole blood aggro-meter, Model 500 (Chrono-log Corporation, Havertown, Pennsylvania). A 500 ,uL whole blood sample was diluted with 500 1AL of isotonic saline in a 1 mL plastic cuvette containing a siliconized stir bar, then placed in the aggro-meter heating block for mixing and warming to 370C for 5 min. Upon insertion of the impedance electrode, the calibration and the gain controls were used to set the recorder at 5 ohms. After the addition of an agonist, the change in impedance or aggregation curve was recorded at a paper speed of 2.5 cm/ min. The final concentration of agonists in whole blood was as follows: ADP 10 ,imol and collagen 5 ,ug/ mL (Chrono-log Corporation, Havertown, Pennsylvania), arachidonic acid 50 gAg/ mL and epinephrine 1 x 10-5 mol (Bio-Data Corporation, Hatboro, Pennsylvania). Platelet-rich plasma (PRP) aggregation was performed using the Chronolog aggro-meter, model 500. Platelet-rich plasma was prepared by centrifugation of blood at 100 g for 20 min at room temperature. The supernatant was then transferred to a clean plastic tube. The citrated blood was then recentrifuged at 1500 g for 10 min and the platelet-poor plasma (PPP) used to adjust the PRP to a platelet count of 300 x 109/ L for aggregation assay. The following agonists were employed at final concentration in PRP as follows: ADP 10 ,imol, collagen 5 ,ug/mL and thrombin 0.5 units/ mL (Data-Fi, Baxter-Canlab, Edmonton, Alberta). SEROTONIN RELEASE
Labelled (14C)-serotonin was used as a marker to measure release of platelet dense granule constituents as described by Sheridan et al (4). The following agonists were employed at final concentrations of PRP as follows: ADP 1 x 10-5 mol/L and collagen 100 mg/ L (Sigma Diagnos-
tics, St. Louis, Missouri). PLATELET MEMBRANE GLYCOPROTEIN ELECTROPHORESIS
Platelet-rich plasma from an affected Simmental cow and a normal cow was sent to Drs. David Phillips and Israel Charro at the Gladstone Foundation, University of San Francisco, San Francisco, California for platelet glycoprotein electrophoresis.
RESULTS
secretion of constituents which attract more platelets to aggregate with Blood from bleeding Simmental adherent platelets to form a platelet cattle had advanced clot retraction, plug (5). Platelet aggregation follows a series similar to that of normal cattle, at 1 h of events within the platelets resulting of incubation. Thrombopathic platelets failed to in exposure of receptors for fibrinogen aggregate in response to all agonists in and other adhesive proteins. The whole blood and platelet-rich plasma fibrinogen molecule has multiple (Table I). Although there appeared to recognition sites for platelet receptors be a minor response to thrombin by and thus may serve to link adjacent the thrombopathic platelets it was platelets (6,7). The platelet membrane assumed to be insignificant when glycoproteins which bind fibrinogen compared to the response of normal have been extensively studied in platelets. Normal cattle failed to humans. They are two molecules aggregate in response to arachidonic designated glycoproteins (GP) Ilb and Illa which traverse the platelet acid and epinephrine. Release of '4C-serotonin by throm- membrane and are held as a complex bopathic Simmental platelets from by calcium. There are approximately one cow was comparable to the release 50,000 GP Ilb-Illa complexes per obtained with normal bovine platelets human platelet which takes it the most abundant platelet surface protein (6). (Table II). Inherited bleeding disorders have Electrophoretic studies of major platelet glycoproteins failed to reveal been described which are associated any differences between a normal cow with impaired in vitro platelet aggreand an affected Simmental cow. gation. Glanzmann's thrombasthenia occurs in humans with failure of in vitro fibrinogen binding and aggregation due to abnormal platelet memDISCUSSION brane fibrinogen binding proteins, i.e. Platelets are essential contributors GP Ilb-IlIa complexes. A thrombopato the early stages of hemostasis. thia occurs in some Basset Hound dog Vascular injury with exposure of families characterized by failure of in underlying collagen results in platelet vitro fibrinogen binding and aggregaadhesion. Adhesion is mediated by tion due to abnormal fibrinogen Von Willebrand protein, a large receptor availability with no quantitamultimer located within and beneath tive abnormalities in Ilb-Illa comendothelial cells and within platelets. plexes (8). At this point it would appear that It attaches to specific receptors on the platelet membrane and to collagen the bleeding disorder in Simmental thus effecting adhesion. Adhesed cattle has comparable and contrasting platelets undergo activation with features to Glanzmann's thrombasthe-
TABLE I. Platelet aggregation responses in normal and thrombopathic Simmental cattle Whole blood platelet Aggregation (ohms)
Normal N = 25
Thrombopathic
25 ± 6a 25 + 3 I ±3 0
0 0
N=6
N=2
21 +2 11 +1 30 11
0 0.9 ±0.7 2.5 +1.5
N=7
Agonists: ADP
Collagen Arachidonic acid Epinephrine Platelet rich plasma Platelet aggregation (ohms) Agonists: ADP
Collagen Thrombin aMean ± standard deviation
ND ND
ND = Not done
395
Basset Hound thrombopathia is an autosomal recessive disorder characterized by failure of platelet aggregation in response to ADP and collagen. Clot 14C Serotonin release retraction is normal in thrombopathic (% of maximum release)a Normal Thrombopathic Basset Hound dogs and Simmental Agonist cow cow cattle. In contrast to bleeding SimmenCollagen 100 100 tal cattle however thrombopathic ADP 77 18 Basset Hound platelets aggregated in None ND 10 response to thrombin and had impaired aMaximum release was determined by the dense granule secretion of 14Cagonist which yielded the highest number of serotonin. Basset Hound thrombopacounts thic platelets exhibited normal shape ND = Not done change in response to various stimuli and had normal ultrastructural appearnia and the Basset Hound thrombopa- ance (8). Similar studies are indicated thia. Most patients with Glanzmann's on platelets from bleeding Simmental thrombasthenia either lack, or show a cattle. modified clot retraction whereas as Stimulation of platelets with thromnoted in this study and by Kociba the bin or ADP causes an increase in blood from bleeding Simmental cattle intracellular ionized calcium which is undergoes good clot retraction (1). a prerequisite for the secretory and The failure of in vitro aggregation in aggegregatory responses of platelets. response to ADP, collagen and Studies of intracellular calcium thrombin is similar in Glanzmann's responses in thrombopathic Basset disease and thrombopathic Simmen- Hound platelets by Catalfamo and tal cattle. The failure of normal bovine coworkers (8) suggests that such platelets to aggregate in response to responses are impaired, resulting in arachidonic acid and epinephrine has failure of expression of fibrinogen been reported by Meyers (9). Glanz- binding receptors on the platelet mann's patients' platelets have normal surface. Recently Patterson et al (12) dense granule secretion as was true of have shown that thrombopathic the platelets from one bleeding Basset Hound platelets, despite failure Simmental cow (10). Most children to aggregate, are capable of binding with Glanzmann's thrombasthenia fibrinogen. Based on this finding they have electrophoretically demonstrable speculate that the defect in platelet abnormalities in the Ilb-Illa complex function must lie within intracellular (10). Recently however the aggrega- signalling mechanisms which occur tion defect observed with Glanz- subsequent to fibrinogen-receptor mann's thrombasthenia has been interaction. associated with both quantitative and These studies as well as those qualitative alterations in the GP Ilb- previously reported on Simmental Illa complex ( 11). No quantitative cattle demonstrate that the platelet abnormalities of GP Ilb-Illa were abnormality that occurs in these revealed by platelet electrophoresis in animals is unique, when compared to one affected Simmental cow. This other species. Further characterizadoes not preclude an amino acid tion of this abnormality will hopefully substitution at a strategic location in precisely define the platelet function one of the glycoproteins, and fibrino- defect and may allow us to develop an gen binding studies are indicated. assay to detect the carrier state. TABLE II. Serotonin release in citrated platelet-rich plasma from one normal cow and one thrombopathic Simmental cow
396
ACKNOWLEDGMENTS The technical assistance of Dennis Olexson is gratefully acknowledged. Thanks are also due to Dr. Marion Jackson for reading the manuscript and Sandra Mayes for typing the manuscript.
REFERENCES 1. KOCIBA GJ. Partial characterization of a hemostatic defect in Simmental cattle. Vet Clin Pathol 1980; 9: 46-47. 2. LEIPOLD H, MOORE W. Bovine thrombopathia. Listed by Dodds WJ in First Registry of Animal Models of Thrombosis and Hemorrhagic Diseases. ILAR News 1977; 21: A14. 3. SEARCY GP, PETRIE L. Clinical and laboratory findings of a bleeding disorder in Simmental cattle. Can Vet J 1990; 31: 101103. 4. SHERIDAN D, CARTER C, KELTON JG. A diagnostic test for heparin-induced thrombocytopenia. Blood 1986; 67: 27-30. 5. COLLER BS. Disorders of platelets. In: Ratnoff OP, Forbes CD, eds. Disorders of Hemostasis. Montreal: Grune & Stratton, Inc., 1984: 73-176. 6. PHILLIPS DR, CHARO IF, PARISE LV, FITZGERALD LA. The platelet membrane glycoprotein complex. Blood 1988; 71: 831-843. 7. MARGUERIE GA, PLOW EF. The fibrinogen-dependent pathway of platelet aggregation. Ann NY Acad Sci 1983; 408: 556-566. 8. CATALFAMO JL, RAYMOND SL, WHITE JG, DODDS JW. Defective platelet-fibrinogen interaction in hereditary canine thrombopathia. Blood 1986; 67: 1568-1577. 9. MEYERS KM. Pathobiology of animal platelets. Adv Vet Sci Comp Med 1985; 30: 131-165. 10. RAO AK, HOLMSEN H. Congenital disorders of platelet function. Semin Hematol 1986; 23: 102-118. 11. FITZGERALD LA, CHEDIAK J, JENNINGS LK, STROTHER SV, PHILLIPS DR. Identification of molecular variants of Glanzmann's thrombasthenia. Blood 1985; 66: 289a. (Abstr). 12. PATTERSON WA, ESTRY DW, SCHWARTZ KA, BORCHERT RD, BELL TG. Absent platelet aggregation with normal fibrinogen binding in Bassett Hound hereditary thrombopathy. Thromb Haemost 1989; 101 1-1015.
