Immunosuppressive factor(s) extracted from lymphoid cells of nonresponder mice primed with L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) III. Immunochemical properties of the GAT-specific suppressive factor.

Abstract

The GAT-specific suppressor T[thymus-derived]-cell factor (GAT-TsF) extracted from lymphoid cells from GAT-primed, nonresponder DBA/1 mice was partially characterized. It is a protein that has affinity for GAT and determinants encoded by the I region of the H-2 complex. On the basis of specificity and avidity, GAT-TsF resembles anti-GAT-MBSA [methylated bovine serum albumin] antibodies produced by DBA/1 mice. This is true despite the fact that it is too small to be classical antibody and has no constant-region determinants of H or L chains. GAT or a fragment of GAT is associated with the GAT-TsF. GAT-TsF was partially purified from the crude extract by absorption to GAT-sepharose and elution with 0.4-0.6 M KCl. GAT-TsF purified on the basis of its affinity for GAT bears I-region determinants but not detectable GAT or GAT fragment.