Multiple sclerosis: recent advances in diagnosis, clinical immunology and virology The cause of multiple sclerosis (MS) remains unknown. Since the first clinical description in the latter part of the 19th century1 MS has remained a clinical diagnosis and despite advances in the knowledge of the pathogenesis of this suspected autoimmune disease its clinical course is unpredictable. Most physicians who manage patients with MS recognize that the prognosis is much more benign than was previously thought. The most recent data2 suggest that the life expectancy of MS patients is almost 75% of normal, and that most patients 25 or 30 years after onset of the disease remain independent, though most have some permanent neurologic disability. As more knowledge accumulates on the cause of MS there will be a corresponding increase in the need for accurate early diagnosis. Since no therapy is available, there is also an urgent need to establish an accurate prognosis. Recent advances in the knowledge of the pathophysiology and clinical immunology will help in both early diagnosis and accurate prognosis. The diagnosis of MS, though primarily clinical, can be aided by accurate analysis of cerebrospinal fluid (CSF). The proportion of gamma globulin, as related to the total protein, is known to be elevated in MS, mainly owing to the presence of immunoglobuun G (IgG), which appears to be synthesized within the central nervous system.3 Moreover IgG tends to appear as distinct bands that can be seen in protein electrophoresis of concentrated CSF.4 The appearance of this "oligoclonal" pattern of the CSF gamma globulin is highly suggestive of MS. A similar pattern can be seen in subacute sclerosing panencephalitis and in neurosyphilis. The main clinical diagnostic criterion is the demonstration that lesions have occurred in the central nervous system and have disseminated in both time and space.5 Neurologists frequently see patients who have a progressive disorder involving one particular area of the nervous system with dissemination in space. Recent pathophysiologic studies have demonstrated that cerebral potentials produced by patterned stimulation of the visual system can be measured accurately.8 The latency of this response can be quantitated, and in demyelinating lesions involving the visual pathways there is a delay in the arrival of this evoked potential at the occipital pole. This system can now be used to identify lesions in patients
who have no symptoms relating to the optic system or the cerebral hemispheres. Similar studies of delay in transmission can be applied to the brain stem. Delay in the pontine blink reflex latency suggests lesions in the brain stem itself.7 With computerized tomography more subtle non-space-occupying lesions in the cerebral hemispheres and brain stem can now be identified.8 It is hoped that this technique will soon be adapted to the spinal cord. All three of these studies can be used to identify more clearly the dissemination of lesions in space throughout the nervous system. As an outgrowth of the study of histocompatibility (HLA) antigens in humans in clinical organ transplantation, a number of diseases have been found to be associated with certain HLA antigens. At the first international symposium on HLA antigens and disease, held in June 1976 in Paris, MS was prominent in the discussions. The HLA antigens A3, B7, B 18 and more recently Dw2 (LD-7a) have been found more frequently in the MS population than in control populations.9 An even stronger association has been found with Blymphocyte antigens and MS,10 but this remains to be confirmed. The currently accepted theory is that there is a relation between HLA markers and genetically determined increased susceptibility to certain diseases. MS is uncommon in some racial groups that do not carry these particular HLA antigens, which suggests that patients and families carrying these HLA types have an increased susceptibility to the disease. Workers in Denmark" have suggested that the prognosis in MS is also related to the presence or absence of certain HLA antigens. More than 50% of individuals with MS carry the HLA antigen Dw2. The Danish workers have suggested that these patients also have a poorer prognosis than do MS patients not carrying this antigen. Our results have not confirmed this, but additional studies are in progress. Since susceptibility to virus infection, as well as the control of immunologic responses, seems to be determined by the major histocompatibility complex in animals, it is intriguing to speculate on the possible relation of virus infections to the cause and pathogenesis of MS. Virus studies, with inoculation of animals, have been done since Pierre Marie first suggested that the cause of MS might be infectious.1 Most studies have not borne fruit. There is indirect
evidence that measles might be related to MS. Patients with MS and their siblings carry higher concentrations of measles antibody than does the normal population.12 Koldovsky and colleagues13 have reported the presence of a replicating agent in the tissue of patients dying from MS that is specific for the disease, though they are much more cautious than the press reports were concerning this finding. Undoubtedly some factor is present in the tissue of MS patients that affects the ability of the mouse to maintain adequate numbers of polymorphonuclear cells in the blood. Another group has found evidence of measles antigen in the intestinal mucosa of MS patients.14 There is no recognized long-term medical therapy for MS, though many therapeutic modalities are under study. These range from agents such as the innocuous linoleic acid,'1 through transfer factor as an immunologic stimulus,'6 to the complication-ridden massive immunosuppression being used in Great Britain and Europe.17 Workers in Toronto are evaluating the possible use of myelin basic protein18 as immunotherapy in acute relapses. If we could establish an accurate prognosis for patients with MS we might be in a better position to assay these particular modes of therapy. With a marker for prognosis (possibly the HLA antigens) we could select for aggressive clinical trials patients in whom a poor prognosis was indicated. Patients with a naturally good prognosis should probably remain untreated. The eventual goal is to make an early accurate diagnosis and to arrest the disease at that point. DONALD W. PATY, MD, FRCP[C] Multiple sclerosis clinic Department of clinical neurological sciences University of Western Ontario London, Ont.
References 1. CHARCOT J-M: Histologie de la sclerose en plaques. Gaz Hop (Paris) 41: 554, 1868 2. KURI-ZKE JF, BEEaE GW, NAGLER B, et al: Studies on the natural history of multiple
sclerosis. Arch Neurol 22: 215, 1970 3. ToustTEuoi-rs W: On cerebrospinal fluid immunoglobulin-G (IgG) quotients in multiple sclerosis and other diseases. .! Neural Sci 10: 279, 1970
4. LINK H, MULLER R: Immunoglobulins in multiple sclerosis and infections of the nervous system. Arch Neurol 25: 326, 1971 5. SCHUMACKER
GA,
BEEBE GW,
KIBLER
RF,
et al: Problems of experimental trials of therapy in multiple sclerosis. Ann NY Acad Sd 122: 552, 1965 6. HALLIDAY AM, MCDONALD WI, MusissN
J:
Delayed visual evoked response in optic neuritis. Lancet 1: 982, 1972 7. KIMURA J: Alteration of the orbicularis oculi reflex by pontine lesions. Arch Neural 22: 156, 1970 8. WARREN KG, BALL MJ, PATY DW, et al:
Computer tomography in disseminated scle-
rosis. Can J Neural Sd 3: 211, 1976
CMA JOURNAL/JULY 23, 1977/VOL. 117 113
9. JERSILD C, DUPONT B, FOG T, et al: Histocompatibility determinants in multiple sclero-
sis. Transplant Rev 22: 148: 1975
10. WINCHESTER RJ, EBERS G, Fu SM, Ct al:
B-cell alloantigen Ag 7a in multiple sclerosis (C). !Jancet 2: 814, 1975 11. JERSILD C, HANSEN GS, SVEJGAARD A, et al: Histocompatibility determinants in multiple sclerosis, with special reference to clinical course. Lancet 2: 1221, 1973 12. PATE DW, FURESZ J, BoucHaR DW, et al: Measles antibodies as related to HLA types
in multiple sclerosis. Neurology 26: 651, 1976
13. KOLDOVSKY U, KOLDOVSKY P, HENLE G, et al:
Multiple sclerosis-associated agent: transmission to animals and some properties of the agent. Infect Immun 12: 1355, 1975 14. PERT5CHUK LP, CooK AW, GUPTA J: Measles antigen in multiple sclerosis: identification in the jejunum by immunofluorescence. Life Sd 19: 1603, 1976
15. MILLAR
JHD,
ZILKHA
KJ,
LANGMAN
MJS,
et al: Double-blind trial of linoleate supplementation of the diet in multiple sclerosis. Br Med 1 1: 765, 1973
16. JERSILD C, PLATZ P, THOMSEN M, et at: Transfer-factor therapy in multiple sclerosis
(C). Lance: 2: 1381, 1973 17. RING J, SEIFERT J, LOB G, et al: Intensive immunosuppression in the treatment of multiple sclerosis. Lancet 2: 1093, 1974
18. EYLAR EH: Experimental allergic encephalomyelitis and multiple sclerosis, in Multiple Sclerosis: immunology, Virology, and Ultra-
structure, WOLFORAM F, ELLIsoN 0, STEVENS J, et al (eds), New York, Acad Pr, 1972, pp
449-81
Biologic role of lymphocytes Almost 100 years ago Ehrlich and Lazarus1 established that lymphocytes - small "round cells" - were independent cellular forms. Since then much information has accumulated on their functions and biologic role. Lymphocytes play a key role in human immunity, and aberrant lymphocyte function contributes to the pathogenesis of such conditions as immune deficiency states, rejection of transplanted organs, autoimmune diseases and lymphoplasmacytic neoplasms. Lymphocytes are motile, globular cells, 4 to 20 j. in diameter. They are unevenly distributed in the body: 0.2% in the circulation, approximately 5% in the bone marrow, 7% in the lymphatic system and the rest scattered throughout the tissues. Lymphocytes are formed in the thymus gland, lymph nodes, spleen, bone marrow and other lymphoid tissues such as the appendix, Peyer's patches, tonsils and adenoids. Lymphocytes have been divided into two groups, T and B, according to the pathway of their differentiation. Both types arise from a common stem cell in the bone marrow. During embryologic development T (thymus-derived) stem cells migrate to the thymus gland, where environmental influences induce proliferation and further maturation of the thymocytes. These cells then migrate from the thymus and mature within specific areas of the lymph nodes and spleen. A subpopulation of immature T-lymphocytes acts as T stem cells in these peripheral tissues to perpetuate the T-lymphocyte line when involution of the thymus occurs in adult life. T-lymphocytes are responsible for cellular immunity against microorganisms. They initiate graftversus-host reactions by generating proliferative and cytotoxic responses to alloantigens. Moreover they amplify, help or suppress B-lymphocytes. B (bursa-derived)-lymphocytes are so named because in chickens they originate from a hindgut organ called the bursa of Fabricius. Whether an analogous organ exists in humans remains to be elucidated. After differentiation
from lymphoid stem cells in the bone marrow, virgin B cells (not previously having antigen contact) migrate to their defined areas of lymph nodes and spleen. Under the influence of antigens these cells proliferate into a morphologically lymphocytic, memory-cell population or differentiate further into plasma cells. This process probably requires cooperation of T-lymphocytes and macrophages. The main function of B-lymphocytes and plasma cells is to synthesize and excrete immunoglobulins (antibodies). The immune system mediated by Tand B-lymphocytes may also direct and augment the nonspecific immune response subserved by phagocytic cells, polymorphonuclear leukocytes and macrophages. Detection of T- and B-lymphocyte populations has greatly facilitated analysis of the cellular aspects of immunologic phenomena. Each population has distinct membranous or surface markers of two types: (a) antigens or immunoproteins on the membrane that can be detected by labelled antibodies; and (b) receptors on the surface that recognize immunoproteins or antigens. T-lymphocytes account for 80 to 90% of the peripheral blood lymphocyte population. Several surface markers are available to identify T-lymphocytes; the most common is based on the presence of receptors for sheep red blood cells (SRBCs). A mixture of Tlymphocytes and SRBCs in vitro results in clusters of SRBCs around the cells, termed E-rosettes. Enumeration of these rosette-forming cells provides a measure of the number of T-lymphocytes. Since the surface of T-lymphocytes is antigenically distinct from that of B-lymphocytes, immunologically specific antibody for the T-lymphocytes may be produced in animals. Such antisera may be labelled as fluorescent conjugates or used as cytotoxins to identify T-lymphocytes. These cells also possess surface structures antigenically similar to human brain, enabling labelled antibrain antibody to be used for their identification.
114 CMA JOURNAL/JULY 23, 1977/VOL. 117
Markers for B-lymphocytes have also been developed. The most widely used is one based on the presence of surface immunoglobulins (5-Ig), which are synthesized within the B-lymphocyte and exteriorized. Most circulating B-lymphocytes have 1gM or IgD, or both, on their surface, while a minority have IgA or IgG. 5-Ig may be demonstrated by fluorescinated antisera directed against the various classes of immunoglobulins. In addition to 5-Ig, B-lymphocytes possess on their surface receptors for the Fc (crystallizable fragment) portion of the IgG molecule. B-lymphocytes with Fc receptors will bind to fluorochrome-labelled aggregated IgG or antigen-antibody complexes and will form rosettes with erythrocytes coated with IgG antibody. Like T-lymphocytes, B-lymphocytes may be identified by antisera produced in animals. B-lymphocytes also possess a receptor for the third component of complement (C'3) and hence form rosettes with SRBCs coated with antibody and complement (erythrocyte-antibody-complement rosettes). In general, B-lymphocytes account for 10 to 20% of the peripheral blood lymphocyte population as enumerated by the above techniques. B-lymphocyte enumeration can be difficult since monocytes also possess Fc and complement receptors. Monocytes may be identified by means of polystyrene beads, which are phagocytosed and visualized by phase-contrast microscopy and excluded from the B-lymphocyte count, or by other techniques. In addition to the two major groups of lymphocytes, two minor groups have been identified - one devoid of surface markers ("null" cells) and another that has double (T and B) surface markers (D cells). Whether these populations represent separate subsets is still unclear. Lymphocyte subpopulations may also be distinguished by in vitro assays of functions. Such functions include proliferation in response to nonspecific
who have no symptoms relating to the optic system or the cerebral hemispheres. Similar studies of delay in transmission can be applied to the brain stem. Delay in the pontine blink reflex latency suggests lesions in the brain stem itself.7 With computerized tomography more subtle non-space-occupying lesions in the cerebral hemispheres and brain stem can now be identified.8 It is hoped that this technique will soon be adapted to the spinal cord. All three of these studies can be used to identify more clearly the dissemination of lesions in space throughout the nervous system. As an outgrowth of the study of histocompatibility (HLA) antigens in humans in clinical organ transplantation, a number of diseases have been found to be associated with certain HLA antigens. At the first international symposium on HLA antigens and disease, held in June 1976 in Paris, MS was prominent in the discussions. The HLA antigens A3, B7, B 18 and more recently Dw2 (LD-7a) have been found more frequently in the MS population than in control populations.9 An even stronger association has been found with Blymphocyte antigens and MS,10 but this remains to be confirmed. The currently accepted theory is that there is a relation between HLA markers and genetically determined increased susceptibility to certain diseases. MS is uncommon in some racial groups that do not carry these particular HLA antigens, which suggests that patients and families carrying these HLA types have an increased susceptibility to the disease. Workers in Denmark" have suggested that the prognosis in MS is also related to the presence or absence of certain HLA antigens. More than 50% of individuals with MS carry the HLA antigen Dw2. The Danish workers have suggested that these patients also have a poorer prognosis than do MS patients not carrying this antigen. Our results have not confirmed this, but additional studies are in progress. Since susceptibility to virus infection, as well as the control of immunologic responses, seems to be determined by the major histocompatibility complex in animals, it is intriguing to speculate on the possible relation of virus infections to the cause and pathogenesis of MS. Virus studies, with inoculation of animals, have been done since Pierre Marie first suggested that the cause of MS might be infectious.1 Most studies have not borne fruit. There is indirect
evidence that measles might be related to MS. Patients with MS and their siblings carry higher concentrations of measles antibody than does the normal population.12 Koldovsky and colleagues13 have reported the presence of a replicating agent in the tissue of patients dying from MS that is specific for the disease, though they are much more cautious than the press reports were concerning this finding. Undoubtedly some factor is present in the tissue of MS patients that affects the ability of the mouse to maintain adequate numbers of polymorphonuclear cells in the blood. Another group has found evidence of measles antigen in the intestinal mucosa of MS patients.14 There is no recognized long-term medical therapy for MS, though many therapeutic modalities are under study. These range from agents such as the innocuous linoleic acid,'1 through transfer factor as an immunologic stimulus,'6 to the complication-ridden massive immunosuppression being used in Great Britain and Europe.17 Workers in Toronto are evaluating the possible use of myelin basic protein18 as immunotherapy in acute relapses. If we could establish an accurate prognosis for patients with MS we might be in a better position to assay these particular modes of therapy. With a marker for prognosis (possibly the HLA antigens) we could select for aggressive clinical trials patients in whom a poor prognosis was indicated. Patients with a naturally good prognosis should probably remain untreated. The eventual goal is to make an early accurate diagnosis and to arrest the disease at that point. DONALD W. PATY, MD, FRCP[C] Multiple sclerosis clinic Department of clinical neurological sciences University of Western Ontario London, Ont.
References 1. CHARCOT J-M: Histologie de la sclerose en plaques. Gaz Hop (Paris) 41: 554, 1868 2. KURI-ZKE JF, BEEaE GW, NAGLER B, et al: Studies on the natural history of multiple
sclerosis. Arch Neurol 22: 215, 1970 3. ToustTEuoi-rs W: On cerebrospinal fluid immunoglobulin-G (IgG) quotients in multiple sclerosis and other diseases. .! Neural Sci 10: 279, 1970
4. LINK H, MULLER R: Immunoglobulins in multiple sclerosis and infections of the nervous system. Arch Neurol 25: 326, 1971 5. SCHUMACKER
GA,
BEEBE GW,
KIBLER
RF,
et al: Problems of experimental trials of therapy in multiple sclerosis. Ann NY Acad Sd 122: 552, 1965 6. HALLIDAY AM, MCDONALD WI, MusissN
J:
Delayed visual evoked response in optic neuritis. Lancet 1: 982, 1972 7. KIMURA J: Alteration of the orbicularis oculi reflex by pontine lesions. Arch Neural 22: 156, 1970 8. WARREN KG, BALL MJ, PATY DW, et al:
Computer tomography in disseminated scle-
rosis. Can J Neural Sd 3: 211, 1976
CMA JOURNAL/JULY 23, 1977/VOL. 117 113
9. JERSILD C, DUPONT B, FOG T, et al: Histocompatibility determinants in multiple sclero-
sis. Transplant Rev 22: 148: 1975
10. WINCHESTER RJ, EBERS G, Fu SM, Ct al:
B-cell alloantigen Ag 7a in multiple sclerosis (C). !Jancet 2: 814, 1975 11. JERSILD C, HANSEN GS, SVEJGAARD A, et al: Histocompatibility determinants in multiple sclerosis, with special reference to clinical course. Lancet 2: 1221, 1973 12. PATE DW, FURESZ J, BoucHaR DW, et al: Measles antibodies as related to HLA types
in multiple sclerosis. Neurology 26: 651, 1976
13. KOLDOVSKY U, KOLDOVSKY P, HENLE G, et al:
Multiple sclerosis-associated agent: transmission to animals and some properties of the agent. Infect Immun 12: 1355, 1975 14. PERT5CHUK LP, CooK AW, GUPTA J: Measles antigen in multiple sclerosis: identification in the jejunum by immunofluorescence. Life Sd 19: 1603, 1976
15. MILLAR
JHD,
ZILKHA
KJ,
LANGMAN
MJS,
et al: Double-blind trial of linoleate supplementation of the diet in multiple sclerosis. Br Med 1 1: 765, 1973
16. JERSILD C, PLATZ P, THOMSEN M, et at: Transfer-factor therapy in multiple sclerosis
(C). Lance: 2: 1381, 1973 17. RING J, SEIFERT J, LOB G, et al: Intensive immunosuppression in the treatment of multiple sclerosis. Lancet 2: 1093, 1974
18. EYLAR EH: Experimental allergic encephalomyelitis and multiple sclerosis, in Multiple Sclerosis: immunology, Virology, and Ultra-
structure, WOLFORAM F, ELLIsoN 0, STEVENS J, et al (eds), New York, Acad Pr, 1972, pp
449-81
Biologic role of lymphocytes Almost 100 years ago Ehrlich and Lazarus1 established that lymphocytes - small "round cells" - were independent cellular forms. Since then much information has accumulated on their functions and biologic role. Lymphocytes play a key role in human immunity, and aberrant lymphocyte function contributes to the pathogenesis of such conditions as immune deficiency states, rejection of transplanted organs, autoimmune diseases and lymphoplasmacytic neoplasms. Lymphocytes are motile, globular cells, 4 to 20 j. in diameter. They are unevenly distributed in the body: 0.2% in the circulation, approximately 5% in the bone marrow, 7% in the lymphatic system and the rest scattered throughout the tissues. Lymphocytes are formed in the thymus gland, lymph nodes, spleen, bone marrow and other lymphoid tissues such as the appendix, Peyer's patches, tonsils and adenoids. Lymphocytes have been divided into two groups, T and B, according to the pathway of their differentiation. Both types arise from a common stem cell in the bone marrow. During embryologic development T (thymus-derived) stem cells migrate to the thymus gland, where environmental influences induce proliferation and further maturation of the thymocytes. These cells then migrate from the thymus and mature within specific areas of the lymph nodes and spleen. A subpopulation of immature T-lymphocytes acts as T stem cells in these peripheral tissues to perpetuate the T-lymphocyte line when involution of the thymus occurs in adult life. T-lymphocytes are responsible for cellular immunity against microorganisms. They initiate graftversus-host reactions by generating proliferative and cytotoxic responses to alloantigens. Moreover they amplify, help or suppress B-lymphocytes. B (bursa-derived)-lymphocytes are so named because in chickens they originate from a hindgut organ called the bursa of Fabricius. Whether an analogous organ exists in humans remains to be elucidated. After differentiation
from lymphoid stem cells in the bone marrow, virgin B cells (not previously having antigen contact) migrate to their defined areas of lymph nodes and spleen. Under the influence of antigens these cells proliferate into a morphologically lymphocytic, memory-cell population or differentiate further into plasma cells. This process probably requires cooperation of T-lymphocytes and macrophages. The main function of B-lymphocytes and plasma cells is to synthesize and excrete immunoglobulins (antibodies). The immune system mediated by Tand B-lymphocytes may also direct and augment the nonspecific immune response subserved by phagocytic cells, polymorphonuclear leukocytes and macrophages. Detection of T- and B-lymphocyte populations has greatly facilitated analysis of the cellular aspects of immunologic phenomena. Each population has distinct membranous or surface markers of two types: (a) antigens or immunoproteins on the membrane that can be detected by labelled antibodies; and (b) receptors on the surface that recognize immunoproteins or antigens. T-lymphocytes account for 80 to 90% of the peripheral blood lymphocyte population. Several surface markers are available to identify T-lymphocytes; the most common is based on the presence of receptors for sheep red blood cells (SRBCs). A mixture of Tlymphocytes and SRBCs in vitro results in clusters of SRBCs around the cells, termed E-rosettes. Enumeration of these rosette-forming cells provides a measure of the number of T-lymphocytes. Since the surface of T-lymphocytes is antigenically distinct from that of B-lymphocytes, immunologically specific antibody for the T-lymphocytes may be produced in animals. Such antisera may be labelled as fluorescent conjugates or used as cytotoxins to identify T-lymphocytes. These cells also possess surface structures antigenically similar to human brain, enabling labelled antibrain antibody to be used for their identification.
114 CMA JOURNAL/JULY 23, 1977/VOL. 117
Markers for B-lymphocytes have also been developed. The most widely used is one based on the presence of surface immunoglobulins (5-Ig), which are synthesized within the B-lymphocyte and exteriorized. Most circulating B-lymphocytes have 1gM or IgD, or both, on their surface, while a minority have IgA or IgG. 5-Ig may be demonstrated by fluorescinated antisera directed against the various classes of immunoglobulins. In addition to 5-Ig, B-lymphocytes possess on their surface receptors for the Fc (crystallizable fragment) portion of the IgG molecule. B-lymphocytes with Fc receptors will bind to fluorochrome-labelled aggregated IgG or antigen-antibody complexes and will form rosettes with erythrocytes coated with IgG antibody. Like T-lymphocytes, B-lymphocytes may be identified by antisera produced in animals. B-lymphocytes also possess a receptor for the third component of complement (C'3) and hence form rosettes with SRBCs coated with antibody and complement (erythrocyte-antibody-complement rosettes). In general, B-lymphocytes account for 10 to 20% of the peripheral blood lymphocyte population as enumerated by the above techniques. B-lymphocyte enumeration can be difficult since monocytes also possess Fc and complement receptors. Monocytes may be identified by means of polystyrene beads, which are phagocytosed and visualized by phase-contrast microscopy and excluded from the B-lymphocyte count, or by other techniques. In addition to the two major groups of lymphocytes, two minor groups have been identified - one devoid of surface markers ("null" cells) and another that has double (T and B) surface markers (D cells). Whether these populations represent separate subsets is still unclear. Lymphocyte subpopulations may also be distinguished by in vitro assays of functions. Such functions include proliferation in response to nonspecific
