Impact of aging upon DBA/2J B cells.

The influence of age on B lymphocyte phenotype and function in DBA/2J mice was examined. The B cells of this strain express the endogenous minor lymphocyte stimulatory (Mls) retroviral superantigen (SAg) Mls-1a permitting assessment of age-related changes in cognate B cell-T cell interaction. Relative to young DBA/2J mice (< 8 months), old mice (> 17 months) had greater numbers of B cells expressing high levels of IgM and low levels of the CD11b and CD5 antigens characteristic of B-1 B cells. As measured by the T cell proliferative response to Mls, the B cells from old DBA/2J mice had reduced ability to present SAg. Upon interaction with Mls-activated T cells, old B cells secreted more IgM while young B cells made more IgG1, IgG3, and IgG2a. DBA/2J BCL functioned poorly as Mls APCs and made considerably less serum Ig. T cells from old mice exhibited a lower response to SAg and were less capable of promoting B cell differentiation. These results indicate that aging influences the cellular collaboration necessary for humoral immunity.