Significance of a Single-hit Event in the Initiation of Antibody Response

Abstract

THE origin of the physico-chemical and immuno-chemical heterogeneity of immunoglobulin molecules has been a perplexing problem for many years. Recently, evidence has been accumulating which points to variability in the expression of antigen-stimulable progenitor cells as the cause of immunoglobulin heterogeneity. Whether or not this is the case—or whether, for example, the variability may result from non-uniformity of polypeptide chain construction by polysomes—can only be decided when methods are available for analysis of immuno-globulins at various times during response by the progeny of a single precursor cell. Before such clonal investigations can be attempted, it is obviously necessary to have some clear notion about the number and frequency of these precursor cells. This communication presents the results of experiments designed to enumerate such cells in spleen cell suspensions from non-primed and primed mice of two different hybrid strains of various age groups.