Immunologic competence of alveolar cells. II. Modification of the plaque-forming response by inhibitors, tolerance, and chronic stimulation.

Abstract

SUMMARy _ After intranasal immunization of rabbits with either sheep erythrocytes or human serum albumin, plaque-forming cells were detected among cells collected by alveolar lavage. Direct plaque formation was inhibited by 10 JLg of actinomycin D per ml, 10 JLg of puromycin per ml, 0.02 M 2-mercapto­ ethanol, guinea pig anti-rabbit immunoglobulin ~I serum, and antilymphocyte serum. Thus, direct plaque formation required protein synthesis and was mediated by immunoglobulin M antibody. During a primary response to human serum albumin, 75 per cent of the plaque-forming cells could be detected with the direct plaque assay and 25 per cent required anti-rabbit immunoglobulin G serum. After prolonged immunization, two thirds of the plaque-forming cells required the facili­ tating anti-immunoglobulin G serum. Intraperitoneal injection of sheep erythrocytes into newborn rabbits produced a state of tolerance accompanied by inhibition of plaque formation after subse­ quent intranasal immunization. Alveolar exudates contain cells that synthesize immunoglobulin G and immunoglobulinM anti­ bodies. These cells are a likely source of some of the immunoglobulins in respiratory secretions.