Immunoglobulin-specific suppressor T cells.

This article has considered evidence that supports the occurrence and functional importance of suppressor T cells that are directed to B cell targets. Cells with these features have been demonstrated in experimental animals and in humans. The designation "suppressor" comes from the serologic phenotype of these cells as well as from their functional property of noncytotoxic inhibition of B cell function. Distinct suppressor T cells with these properties have been identified that effect antigen-, idiotype-, isotype-, and allotype-specific suppression of B cell function. While such cells had been suspected from earlier studies of normal immune responses, the development of monoclonal B cell models using tumor cells has provided a means to readily detect these suppressor T cells and to investigate the mechanisms by which they mediate their effects. Tumor models have proved to be powerful tools in the effort to identify and analyze the elements that underlie the complexity of immune responses. Combined with the insights provided by molecular genetic approaches and flow cytometry, functional and responsive lymphoid tumor cells are being used with increasing frequency to address basic immunoregulatory issues. An important family of suppressor T cells with B cell targets are those that express surface Fc receptors, elaborate immunoglobulin-binding factors, and appear to participate in the regulation of immunoglobulin heavy chain class expression. In addition to their importance in the regulation of heavy chain class expression during normal immune responses, alterations in FcR+ T cells in a number of disease states may provide clues that will lead to a better understanding of disorders of immune regulation.