Ascaris suum: immune response in the guinea pig. I. Lymphoid cell responses during primary infections.

Abstract The lymphoid cell responses of the mesenteric, hepatic, and mediastinal lymph nodes, of the spleen, and of the Peyer's patches of normal guinea pigs that (a) were orally infected with 10,000 infective eggs of Ascaris suum (Group I), (b) received 10,000 artificially hatched second-stage larvae of A. suum via the mesenteric vein (Group II), or (c) received 1500 third-stage larvae of A. suum via the saphenous vein (Group III) were assessed by antigen-induced lymphocyte-transformation, rosette-formation, and rosette-plaquing techniques. Antigen-induced lymphocyte transformation measured qualitatively the antigen-sensitive cell population, rosette formation measured quantitatively the immunoglobulin-receptored cell population and rosette-plaquing measured quantitatively the receptored antibody-producing and the nonreceptored antibody-producing cell populations. Antigen-induced lymphocyte-transformation and rosette-formation studies showed that the immune response to A. suum was local in character at least for the first 11–12 days of infection as exemplified by the marked responses of the draining lymph nodes at the time the parasite was migrating through the tissues of the host. Rosette-plaquing studies in conjunction with the rosette-inhibition studies showed that the lymphoid cell responses of the draining lymph nodes progressed from an antigen-sensitive state to an immunoglobulin-receptored state, then to a receptored state capable of antibody production and finally to a nonreceptored antibody-producing state. In animals of Group I, the lymphoid cells of the mesenteric, hepatic, and mediastinal lymph nodes formed predominantly IgM and IgE antigen-specific rosettes (peak responses at Days 2, 5, and 7 for the mesenteric, hepatic, and mediastinal nodes, respectively), rosette-plaques (peak responses at Days 5, 7, and 9 for the mesenteric, hepatic, and mediastinal nodes, respectively), and plaques (peak responses at Days 7, 9, and 12 for the mesenteric, hepatic, and mediastinal nodes, respectively). The IgE-responsive cells were appreciably higher in the mediastinal lymph nodes than in the other lymphoid organs studied. The responses of the spleen were predominantly IgM in character and they increased gradually as the infection progressed without showing detectable peak responses. The lymphocytes of the Peyer's patches did not exhibit antigen-specific rosetting, rosette-plaquing, or plaquing responses. In Group II animals (elimination of the bowel phase of the infection) only the hepatic and mediastinal nodes exhibited peak responses and these were similar to those of Group I animals in the type and pattern of the responses and in the time of their sequential appearance. In animals of Group III (elimination of both the bowel and the hepatic phase of the infection) only the mediastinal nodes exhibited peak responses and these were similar to those of Groups I and II in the type (predominantly IgM and IgE) and their sequential pattern but differed in the time of their appearance: Peak antigen-specific rosettes, rosetteplaques, and plaques occurred in the mediastinal nodes of Group III animals at Days 2, 5, and 7 after infection, respectively. In each of the responsive lymphoid organs studied, there occurred a certain population of lymphoid cells which was producing immunoglobulins that were not necessarily specific for the A. suum antigen.