Antibody responses, antitumour antibodies and Ig class and subclass levels in C. parvum treated mice.

This paper summarises the results of extensive studies performed in our laboratory during the past three years aimed at establishing the effect of C. parvum administration on humoral immunity in normal mice and mice previously challenged with viable MC fibrosarcoma cells. This treatment was found to (a) increase the response to thymus dependent and independent antigens, (b) result in the production of circulating immunoglobulins which bound to tumour cells and syngeneic tissues in vitro, and (c) marked increases in the levels of certain immunoglobulins, especially IgG2a and IgG2b. The latter effects were dependent upon the dose and route of injection and were inhibited by the administration of gold salts. Similar though less marked effects were also observed in T cell deprived and nude mice and in normal mice injected with other bacterial adjuvants. The mechanisms by which C. parvum exerts the above serological effects and their relevance to antitumour immunity, will be discussed.