Evidence for an immunoglobulin-dependent antigen-specific helper T cell.

Abstract

Evidence from various systems suggests that thymus-derived [T] lymphocytes can affect the quality of antibody responses by recognizing various portions of the immunoglobulin [Ig] receptor of bone-marrow-derived thymus-independent lymphocytes. A model for this process is proposed involving 2 antigen-specific mature T helper cells, one of which also is specific for Ig determinants. These 2 cells act synergistically. Evidence from adoptive secondary antibody responses demonstrates that both cells are antigen-specific T cells and that the Ig-recognizing T helper cell is absent from experimentally agammaglobulinemic mice. This cell is termed an Ig-dependent T cell because its activation requires the presence of Ig.