Activation of T lymphocytes by the Fc portion of immunoglobulin

Abstract
T lymphocytes are stimulated to release T‐cell‐replacing factors in response to Fc fragments of human IgG. Lyt 1+23 T cells are directly triggered to factor production by Fc subfragments, derived from intact Fc fragments by macrophage‐dependent enzymatic cleavage. These factor(s) replace T cell function in two Fc‐mediated immune responses; induction of polyclonal antibody synthesis, and potentiation of anti‐SRBC responses.