Role of self carriers in the immune response and tolerance. VII. Importance of H-2 antigens in the in vitro induction of tolerance and suppression to hapten-modified self

The ability of trinitrophenylated spleen cells to inhibit the anti-TNP plaque-forming cell response of normal splenocytes to a TNP-immunogen in vitro is well established. Using a 2-stage culture technique, we recently demonstrated that, as in the in vivo model system, suppressor T cells are generated in response to modified self in vitro. In this report, we compare the abilities of 2 cell lines, presumed identical except for the expression of H-2 antigen, to induce tolerance and suppression of the B cell response in vitro in order to analyze the role of H-2 in the response to modified self. The results of the comparison using a single-stage culture reveal that at high cell doses and under optimal coupling conditions (i.e., with 10 mM TNBS solution), TNP-R1^- (H-2K^-, H-2D^-, and TL1,2,3^-) is as effective a blocking agent as TNP-R1⁺ (H-2K⁺, H-2D⁺, and TL1,2,3⁺). At limiting hapten doses however, it is apparent that the H-2 and TL-positive cell line is significantly more inhibitory than its H-2-negative variant. Moreover, comparison of TNP-R1⁺ and TNP-R1^- in the 2-stage culture system reveals that heavily haptenated TNP-R1⁺ induces tolerance and suppression as expected, whereas suboptimally haptenated (with 1 mM TNBS) TNP-R1⁺ could induce tolerance but not suppression. Furthermore, although TNP-R1^- induced tolerance in the preculture as effectively as similarly trinitrophenylated TNP-R1⁺, such H-2-negative cells failed to generate suppressor cells detectable in our cell-mixing protocol. These results demonstrate that tolerance can be induced in vitro by modified self in the absence of detectable suppression, and suggest that suppressor cells may be generated primarily in response to modified major histocompatibility complex encoded determinants.