From Fleas to T Lymphocytes and Beyond: How did I Become an Immunologist, and What Has Resulted from It?

A narrative from a co-author of studies explaining the cellular mechanisms of self/nonself discrimination by the immune system, set against the backdrop of significant advancements in immunology during the last quarter of the 20th century. This review focuses on demonstrating the functional diversity of T cells by identifying their two major subsets: regulatory CD4 and cytotoxic CD8. It also examines the first T-cell receptor (TCR) transgenic mice, providing definitive evidence for both positive and negative selection of immature thymocytes as mechanisms for generating a self-tolerant and MHC-restricted TCR repertoire. The origins of these experiments have been discussed.