Characteristics of a Mechanism Suppressing T-Cell Clonal Expansion in Vivo
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A suppressor system controlling T-cell clonal expansion has been previously postulated. The system under study involves adult male C51BL/6 strain mice being injected i.p. with an allogeneic mastocytoma cell line, (P815 from the DBA/2 strain) resulting in the generation of cytotoxic T-cells. An active suppressor mechanism has been postulated as a control, mechanism for this T-cell clonal expansion system . . These studies sttempt to determine. whether the 'neoplastic nature of the antigen contributed to the existence of the suppressor. Two different approaches were used to study the question. 1) The P815 mastocytoma cells were treated with mitomycin C. No response was observed, and it was determined that the mitomycin C treated cells had died before recognition and response could occur. 2) Unsensitized C57BL/6 spleens were cultured, (previous experiments had shown culturing removes the suppressor) challenged with non-tumor antigen, and assayed for lytic activity The second approach yielded the following results: 1) The sup~ pressor was not due to the nature of the antigen, it exists in unchallenged animals. 2) The suppressor was specific to this particular response, and thus is probably a controlling mechanism. 3) Macrophages do not appear to be the suppressing agent.