Recognition of a naturally occurring idiotype by autologous T cells

Abstract

BONE-MARROW-derived (B) lymphocytes belonging to the same clone bear antigen receptors which share a specific marker (idiotype) with antibodies secreted by their progeny¹. According to the network theory of immunity², immunocompetent B cells recognise each other through a network of idiotype anti-idiotype interactions. This theory implies the existence of B and T cells specific for autologous idio-types. To facilitate detection of such cells it is advantageous to study an immune response of restricted heterogeneity. The immune response of BALB/c mice to phosphoryl-choline (PC) is idiotypically homogeneous: the anti-PC antibodies produced bear almost exclusively the idiotype characteristic of the BALB/c PC-binding myeloma protein TEPC-15 (T15) (ref. 3). T15 is a member of a family of PC-binding myeloma proteins of BALB/c origin, which bear distinct idiotypes⁴. Idiotypes representative of these other proteins are not, however, expressed by BALB/c on immunisation with PC. It has recently been reported that helper T cells from BALB/c mice can discriminate among idiotypes expressed on several of these anti-PC myeloma proteins. These authors did not, however, demonstrate helper T cells specific for the T15 idiotype⁵. This failure was attributed to a state of tolerance induced and maintained by the high levels of immunoglobulin bearing the T15 idiotype in conventional BALB/c mice. In this report we demonstrate the existence of T cells reactive to an autologous idiotype and we discuss the possible regulatory role of these T cells in the immune response to PC.