Choices following antigen entry: antibody formation or immunologic tolerance?

The research briefly summarized here covers 38 years of work in cellular immunology, chiefly devoted to understanding how antigen subserves the antithetical functions of stimulating antibody formation and inducing tolerance. The three interlocking themes running through the work are the development of methods to beat the problem of heterogeneity among lymphocytes by studying single cells and single clones; critical pursuit of antigen-trapping patterns within lymphoid tissues and analysis of consequent cellular events; and construction of models of tolerance that permit the detection of events subtler than direct purging of the B cell repertoire. One of the best features of this adventure has been its international character, the interaction with colleagues in many countries, and the influence that this work, despite its entirely fundamental character, has exerted in the practical world of preventive and clinical medicine.