Changing behavior of surface immunoglobulin on mouse B lymphocytes during immune development. II. Surface immunoglobulin modulation clearly distinguishes two stages of B-cell maturation in the neonate

Antibody-induced modulation of cell surface IgM was used as a probe to explore membrane-related differences between fetal and adult mouse B lymphocytes. Receptor modulation was studied as a function of temperature in B cells obtained from mice of various ages. Plots of the rate of anti-IgM induced movement of receptors with temperature showed discontinuities (changes in slope) at different characteristic temperatures for each cell. In this way, radical differences between the receptor behavior of fetal B cells and adult B cells were evident. Moreover, temperature-dependent rates of internalization of receptor-ligand complexes also were found to clearly distinguish two stages of B lymphocyte maturation in the mouse.