Antigen-dependent leukotriene synthesis and histamine release from IgG1 passively-sensitized guinea pig lungs ex vivo: Relationship between serum levels of antigen-specific IgG1 and mediator synthesis/release
✍ Scribed by J.B. Cheng; J.S. Pillar; M.J. Conklyn; R. Breslow; J.T. Shirley; N.P. Gerard; H.J. Showell
- Publisher
- Elsevier
- Year
- 1990
- Tongue
- English
- Weight
- 896 KB
- Volume
- 3
- Category
- Article
- ISSN
- 0952-0600
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✦ Synopsis
Naive guinea-pigs were passively sensitized with varying amounts of affinity column purified, homologous, anti-ovalbumin IgG1 (anti-OA IgG1) and then examined for a) the capacity of lung tissue to release mediators (histamine and LTB4/LTD4) in response to antigen-challenge ex vivo and b) the attendant circulating levels of anti-OA IgG1. Intraperitoneal administration of anti-OA IgG1 (0.125-0.75 mg/kg) to guinea-pigs facilitated the synthesis of LTB4 (8-25 ng/g lung) and LTD4 (18-80 ng/g) and the release of histamine (1-7 ug/g) from lung tissue after exposure to 10 micrograms/ml of ovalbumin for 20 min ex vivo. Peak levels of mediators were found using 0.5 mg/kg anti-OA IgG1 with an ED50 = 0.35 mg/kg. LTD4/LTB4 synthesis and histamine release were both antigen concentration- and time-dependent, and LT synthesis was observable in non-perfused lungs and in lungs perfused free of blood. Maximum sensitization occurred at 1-2 days post i.p. administration of anti-OA IgG1 and was maintained up to 7 days. Measurement of anti-OA IgG1 using an enzyme-linked immunosorbent assay demonstrated that circulating antibody levels were 2-6 micrograms/ml at the doses which caused sensitization. The level of anti-OA IgG1 found in passively sensitized animals was at least 100-fold less than that found in actively-sensitized guinea-pigs despite the similar magnitude in LTD4/LTB4 synthesized and the amount of histamine released. Using purified antibody, the results demonstrate that in guinea-pigs, IgG1 can play a prominent role in regulating lung LT synthesis and histamine release, and that microgram per ml circulating levels of this antibody are sufficient to sensitize naive lungs.