Int. Archs Allergy appl. Immun. 51: 627-636 (1976)
Passive Cutaneous Anaphylaxis in Guinea Pigs Elicited by Gastric Absorption of Dextran Induced by Acetylsalicylic Acid G. F lemstrôm, N. V. B. M arsden and W. R ichter Department of Physiology and Medical Biophysics, The Biomedical Center, University of Uppsala, and The Research Division, Pharmacia AB, Uppsala
Abstract. Passive cutaneous anaphylaxis (PCA) was elicited in guinea pigs sensi tized with rabbit antidextran by the absorption of dextran macromolecules from the stomach induced by intragastric acetylsalicylic acid. The gastric contents had a pH sufficiently low to maintain the acid mainly in the unionized form since it is the lat ter which alters gastric permeability. The acid concentration required to induce PCA was below that which caused mucosal cell loss or bleeding. The maximal mo lecular weight of the absorbed dextran was approximately 25,000. Dextran was cho sen as antigen because of its well-characterized physical and immunological proper ties. It is suggested that ingestion of acetylsalicylic acid may contribute to sensitiza tion and allergic reactions to antigenic food materials by facilitating their absorp tion from the stomach.
Introduction It has been found previously that unionized acetylsalicylic acid greatly increases gastric absorption of saccharide macromolecules both in vitro and in vivo. While the frog gastric mucosa in vitro is normally not perme able even to the trisaccharide raffinose (mol. wt. 504), dextran molecules with molecular weights of up to a maximum of about 30,000 permeated the mucosa after exposure of the luminal side to unionized acetylsalicylic acid [7]. In the cat stomach in vivo, intragastric unionized acetylsalicylic acid greatly increased the absorption of carboxy 14C inulin (K3W = 5,200) [8]. Such increases in the permeability of the normally tight gastric epithelium raise the question of whether this constitutes a potential path-
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/3/2018 9:45:02 PM
Received: December 17, 1975.
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way for immunologically active macromolecules to gain increased access to the circulation. Since the association between acetylsalicylic acid inges tion and allergic reactions in man is well known [16, 21], we deemed it of interest to study whether the combined presence in the stomach of union ized acetylsalicylic acid and macromolecules could provoke passive cuta neous anaphylaxis (PCA) in guinea pigs sensitized against the latter. The polysaccharide dextran was chosen as a model molecule for these studies because its antigenic activity which is well documented [13, 23] is, within wide limits, essentially independent of the molecular weight [17, 19]. Dextran is also resistant to the acid conditions prevailing in the stomach and like saccharides in general not attacked by pepsin. Finally, the availa bility of different molecular weight fractions allowed an estimate to be made of the size of the molecules which penetrated the gastric mucosa and elicited PCA lesions.
Materials and Methods
Operative Procedure All animals were tracheotomized as soon as sufficient depth of anesthesia was attained. A catheter was then introduced into the stomach via the mouth and the esophagus. In a first series of experiments, the abdomen was then opened by a short median incision in the epigastric region, the position of the catheter tip in the stomach checked by palpation and the stomach lumen isolated from the intestine and esopha gus by ligatures around the pylorus and cardia. Solutions instilled into the stomach could thus not reach the intestine. In the second series of experiments the abdomen was not opened and the posi tion of the catheter tip was checked by palpation through the abdominal wall; pas sage between the stomach and the intestine was thus possible but the operative trau ma was greatly reduced. The catheters used (umbilical artery catheter size 8 Fr., Sherwood Med. Ind. Inc., St. Louis, Mo.) allowed satisfactory emptying of the stomach and were also soft so as to avoid damage to the mucosa. After ligating the pylorus the stomach was washed 4-5 times with 5 ml of isotonic NaCl prewarmed to 37 °C. When the pylorus was not ligated, the stomach was washed only once.
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Albino guinea pigs of both sexes weighing between 300 and 400 g were starved for 20 h. They were kept in cages with mesh bottoms to minimize coprophagy but were allowed free access to water. The anesthetic used was Inactin® (Promonta GMBH, Hamburg, FRG), 80 mg/kg body weight administered intraperitoneally. The body temperature was maintained at 37+0.5 °C by a heater controlled by an intrarectal thermometer.
PCA Induced by Dextran and Acetylsalicylic Acid
629
Dextran Three dextran fractions were used: (1) ‘low’ molecular weight dextran (M„. 3,300, fvtn 1,800); (2) ‘intermediate’ molecular weight dextran (Mw 10,500, fvl„ 6,100), and (3) ‘high’ molecular weight dextran (K),v 70,000, H „ 50,000). Mw is the weight average molecular weight and is the number average molecular weight. The preparation and properties of these fractions have been described ear lier [17]. Passive Cutaneous Anaphylaxis Dextran antiserum (PD4 containing 1.2 mg antidextran/ml) was obtained from rabbits which had been repeatedly immunized with soluble dextran-protein conju gates, emulsified in complete Freund’s adjuvant as described earlier [18]. The ani mals were sensitized as first described by O vary [15]. The hair of the abdominal skin was clipped and 4-6 intradermal sites in the caudal half were then sensitized by injecting 0.1 ml of diluted serum intradermally (corresponding to 0.70 /
Passive Cutaneous Anaphylaxis in Guinea Pigs Elicited by Gastric Absorption of Dextran Induced by Acetylsalicylic Acid G. F lemstrôm, N. V. B. M arsden and W. R ichter Department of Physiology and Medical Biophysics, The Biomedical Center, University of Uppsala, and The Research Division, Pharmacia AB, Uppsala
Abstract. Passive cutaneous anaphylaxis (PCA) was elicited in guinea pigs sensi tized with rabbit antidextran by the absorption of dextran macromolecules from the stomach induced by intragastric acetylsalicylic acid. The gastric contents had a pH sufficiently low to maintain the acid mainly in the unionized form since it is the lat ter which alters gastric permeability. The acid concentration required to induce PCA was below that which caused mucosal cell loss or bleeding. The maximal mo lecular weight of the absorbed dextran was approximately 25,000. Dextran was cho sen as antigen because of its well-characterized physical and immunological proper ties. It is suggested that ingestion of acetylsalicylic acid may contribute to sensitiza tion and allergic reactions to antigenic food materials by facilitating their absorp tion from the stomach.
Introduction It has been found previously that unionized acetylsalicylic acid greatly increases gastric absorption of saccharide macromolecules both in vitro and in vivo. While the frog gastric mucosa in vitro is normally not perme able even to the trisaccharide raffinose (mol. wt. 504), dextran molecules with molecular weights of up to a maximum of about 30,000 permeated the mucosa after exposure of the luminal side to unionized acetylsalicylic acid [7]. In the cat stomach in vivo, intragastric unionized acetylsalicylic acid greatly increased the absorption of carboxy 14C inulin (K3W = 5,200) [8]. Such increases in the permeability of the normally tight gastric epithelium raise the question of whether this constitutes a potential path-
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/3/2018 9:45:02 PM
Received: December 17, 1975.
6 28
F lem strom /M
a r sd en / R ic h t e r
way for immunologically active macromolecules to gain increased access to the circulation. Since the association between acetylsalicylic acid inges tion and allergic reactions in man is well known [16, 21], we deemed it of interest to study whether the combined presence in the stomach of union ized acetylsalicylic acid and macromolecules could provoke passive cuta neous anaphylaxis (PCA) in guinea pigs sensitized against the latter. The polysaccharide dextran was chosen as a model molecule for these studies because its antigenic activity which is well documented [13, 23] is, within wide limits, essentially independent of the molecular weight [17, 19]. Dextran is also resistant to the acid conditions prevailing in the stomach and like saccharides in general not attacked by pepsin. Finally, the availa bility of different molecular weight fractions allowed an estimate to be made of the size of the molecules which penetrated the gastric mucosa and elicited PCA lesions.
Materials and Methods
Operative Procedure All animals were tracheotomized as soon as sufficient depth of anesthesia was attained. A catheter was then introduced into the stomach via the mouth and the esophagus. In a first series of experiments, the abdomen was then opened by a short median incision in the epigastric region, the position of the catheter tip in the stomach checked by palpation and the stomach lumen isolated from the intestine and esopha gus by ligatures around the pylorus and cardia. Solutions instilled into the stomach could thus not reach the intestine. In the second series of experiments the abdomen was not opened and the posi tion of the catheter tip was checked by palpation through the abdominal wall; pas sage between the stomach and the intestine was thus possible but the operative trau ma was greatly reduced. The catheters used (umbilical artery catheter size 8 Fr., Sherwood Med. Ind. Inc., St. Louis, Mo.) allowed satisfactory emptying of the stomach and were also soft so as to avoid damage to the mucosa. After ligating the pylorus the stomach was washed 4-5 times with 5 ml of isotonic NaCl prewarmed to 37 °C. When the pylorus was not ligated, the stomach was washed only once.
Downloaded by: Univ. of California Santa Barbara 128.111.121.42 - 3/3/2018 9:45:02 PM
Albino guinea pigs of both sexes weighing between 300 and 400 g were starved for 20 h. They were kept in cages with mesh bottoms to minimize coprophagy but were allowed free access to water. The anesthetic used was Inactin® (Promonta GMBH, Hamburg, FRG), 80 mg/kg body weight administered intraperitoneally. The body temperature was maintained at 37+0.5 °C by a heater controlled by an intrarectal thermometer.
PCA Induced by Dextran and Acetylsalicylic Acid
629
Dextran Three dextran fractions were used: (1) ‘low’ molecular weight dextran (M„. 3,300, fvtn 1,800); (2) ‘intermediate’ molecular weight dextran (Mw 10,500, fvl„ 6,100), and (3) ‘high’ molecular weight dextran (K),v 70,000, H „ 50,000). Mw is the weight average molecular weight and is the number average molecular weight. The preparation and properties of these fractions have been described ear lier [17]. Passive Cutaneous Anaphylaxis Dextran antiserum (PD4 containing 1.2 mg antidextran/ml) was obtained from rabbits which had been repeatedly immunized with soluble dextran-protein conju gates, emulsified in complete Freund’s adjuvant as described earlier [18]. The ani mals were sensitized as first described by O vary [15]. The hair of the abdominal skin was clipped and 4-6 intradermal sites in the caudal half were then sensitized by injecting 0.1 ml of diluted serum intradermally (corresponding to 0.70 /
