Analysis of antigen‐specific, Ig‐restricted cell‐free material made by I‐J+ Ly‐1 cells (Ly‐1 TsiF) that induces Ly‐2+ cells to express suppressive activity

Abstract

A set of T cells defined by a unique profile of cell surface alloantigens (phenotype Ly‐1⁺2⁻; Qa‐1⁺; I‐J⁺) produces biologically active cell‐free material(s) (Ly‐1 TsiF) which induces another T cell set (cell surface phenotype Ly‐1,2⁺; I‐J⁺; Qa‐1⁺) to participate in the suppression of primary immune responses to heterologous erythrocytes. The suppression is specific for the inducing antigen, and the Ly‐1 TsiF binds antigen in a specific way. The activity of Ly‐1 TsiF can be removed by anti‐I‐J immunosorbents and will not be expressed if the functional producer and acceptor cells do not share gene products that are encoded in or are tightly linked to the V_H portion of the Ig complex. There is no requirement for the Ly‐1 TsiF and its acceptor cell(s) to share major histocompatibility complex gene products. Thus, for optimal induction of antigen‐specific suppression by cell‐free materials from Ly‐1 T cells, three necessary conditions must be met: (a) antigen recognition by Ly‐1 TsiF; (b) the expression of I‐J gene products and (c) identity of V_H‐linked Ig locus gene products (or other products influenced by those genes) on both the inducer molecule and its acceptor cell. The role of the Ig‐linked restriction is particularly intriguing, and its possible meaning is considered in detail.