Active immunization induces lung hyperresponsiveness in the guinea pig. Pharmacologic modulation and triggering role of the booster injection.

In order to investigate whether bronchopulmonary hyperresponsiveness represents a unique property of sensitized lungs, we examined the responses of lungs from either actively sensitized, passively sensitized, or nonsensitized (control) guinea pigs to in vitro bronchoconstriction (BC) and release of thromboxane (TX) B2, 6-keto-PGF1 alpha, and histamine induced by platelet-activating factor (PAF-acether) or leukotriene (LT) D4. Guinea pigs were actively sensitized with 10 micrograms of either ovalbumin or Dermatophagoides farinae extract in AI(OH)3 injected intraperitoneally twice at a 2-wk interval. Seven days after the second injection (booster injection), the lungs were removed, ventilated, and perfused via the pulmonary artery with Krebs solution containing 2.5 g/L bovine serum albumin. In lungs from actively sensitized animals, BC was induced by significantly lower doses of PAF-acether and LTD4 than those required to elicit the same response in control preparations. In addition, sensitized lungs released more TxB2, 6-keto-PGF1 alpha, and histamine in response to PAF-acether and LTD4 than did control lungs. Increased mediator release was also observed upon challenge of lungs from actively sensitized animals with arachidonic acid and histamine. Lungs from guinea pigs passively sensitized with serum from actively sensitized animals did not exhibit increased responsiveness to PAF-acether as compared to control lungs. The hyperresponsiveness induced after booster injection of the antigen occurred concomitantly with an increase in the homocytotropic antibody titer (as measured by passive cutaneous anaphylaxis) and persisted for 3 months after sensitization, when the levels of circulating antibodies and lung response to antigen challenge returned to control values.(ABSTRACT TRUNCATED AT 250 WORDS)