SHARED IDIOTYPIC DETERMINANTS ON B AND T LYMPHOCYTES REACTIVE AGAINST THE SAME ANTIGENIC DETERMINANTS I . Demonstration of Similar or Identical Idiotypes on IgG Molecules and T-Cell Receptors with Specificity for the Same Alloantigens*

The immunocompetent cells that can recognize foreign structures by their own actively synthesized antigen-binding receptors are the lymphocytes (1). Two major groups of lymphocytes exist, with separate functions andwithout ability to transform into each other (2, 3) . One group is called T lymphocytes, due to their dependence on the presence of the thymus for development (2). The second group of cells are called B lymphocytes, after the bursa of Fabricius in birds, where maturation of these B cells do occur (3). T lymphocytes are responsible for the major part of so called cell-bound immune reactions, whereas B lymphocytes produce conventional immunoglobulin antibodies .