The anaphylactic in plaque-forming-cell response in rats sensitized by inhalation or intraperitoneal injection of ovalbumin

Administration of ovalbumin without adjuvant, regardless of whether exposure was by inhalation or by i.p. injection, was relatively ineffective in producing an immune response to ovalbumin. A minimum of five antigen treatments and an elapsed time of at least two weeks after the first antigen treatment were necessary to induce detectable serum hemagglutination titers. Maximum hemagglutination titers of 1:1280 were observed only after 13 antigen treatments and an elapsed time of 25 days.

When antigen was administered with B. Pertussis as an adjuvant, serum hemagglutinins were detectable after either a single inhalation exposure or a single i.p. injection of antigen. Intraperitoneal administration of antigen induced an initially strong IgM response and a comparatively weaker but longer lasting IgG response in the spleen. Respiratory tract tissue contained only a minimal number of both IgM and IgG antibody producing cells. Conversely, after a single inhalation exposure to antigen, RT tissue responded initially with a strong IgM reaction, which was subsequently followed two days later by an even stronger IgG response, but the number of both IgM and IgG immunoglobulin producing cells from the spleen was barely detectable. In contrast, a second antigen treatment four weeks after initial sensitization considerably enhanced the RFC response in both the spleen and RT tissue regardless of whether antigen administration was topical or systemic. Each site had earlier and enhanced production of both IgM and IgG antibodies. Production of IgG was enhanced eight to tenfold and was quantitatively higher than that of IgM which was increased two to threefold. Immunoglobulin E was found equally in RT tissue and in serum regardless of the mode (topical or systemic) of antigen administration.

The effect of splenectomy two weeks prior to sensitization essentially abolished the primary immune response. Splenectomy two weeks after primary sensitization greatly reduced but did not abolish the secondary immune response.