Evolutionary and Developmental Aspects of T-cell Recognition

Abstract

Studies relating to the nature of the antigen-specific T-cell receptor are reviewed in the light of present knowledge of phylogenetic and ontogenetic development. It is suggested that this evidence supports the concept that immunoglobulin (Ig) is the T-cell receptor, and that the following conclusions may be tentatively drawn.

1) T cell membrane Ig differs in its physical and functional properties from that on the B cell membrane.

2) The divergence between the T and B cell surface Ig molecules was apparent at the time of emergence of the ancestors of modern fish.

3) Specific T cell recognition in the form of antigen binding appears early in ontogeny, and is blocked by antisera to Ig.