1856 Suppressor Factor Specific for Lactate Dehydrogenase

Antigen-specific, T cell-derived factors have been the subject of extensive studies as possible mediators of immunoregulatory interactions (reviewed in references 1-3). Functionally, two kinds of factor, helper and suppressor, can be distinguished. The suppressor factors (TsF), x again, fall into two categories, namely, inducer factors (TsiF) that play a role in communication between T cell sets of the suppressor pathway, and effector factors (TseF) that cause ultimate suppression. Because the immune response to a single antigen may involve a multi tude of regulatory factors, it is mandatory to establish a pure source of these mediators for further biological and biochemical studies. To this end, several laboratories have produced T cell lines or T cell hybridomas that secrete monoclonal TsF. While the role of some of these TsF in the suppressor pathway has not yet been determined (4-6), other factors have been shown to possess TsiF (7, 8) or TseF (9-13) activity. Thus, there exists now a battery of monoclonal TsF suitable to study cellular interactions in different suppressor pathways. However, there are other obstacles to these studies, namely, that the cells participating in most known suppressor pathways have not been identified, and the effector functions used as a readout of suppression themselves involve complex cellular interactions (4-6, 9-14). We have characterized recently a suppressor pathway that regulates the immune response to lactate dehydrogenase B (LDHB) (15-17). The suppressor effector (Tse) cell in this system is an Lyt-l+2 + cell that becomes activated by the recognition of LDHB together with E k k k (E~Ep) molecules of antigen-presenting cells (APC) and' by an additional, nonspecific, Tsi cell-derived signal. The target of the Tse cell is a proliferating Lyt-1+2 cell that recognizes LDHB together with the A (A~A~) molecules of the APC. The latter ceils probably include the LDHa-specific T helper (Th) cells, since the strain distribution of responsiveness to LDHB is identical in terms of both T