The lineage relationship between virgin and memory B cells

J11d is expressed on a variety of hemopoietic cells, including B cells. In previous studies, we have shown that B cells are heterogeneous with respect to their levels of J11d expression and that memory B cells are contained within the J11dlo B cell population. In this report, we have further examined the relationship between memory precursors and memory cells. We have found that the ability of J11dlo B cells from unprimed mice to respond to primary antigenic stimulation was generally low; the lowest response occurred following immunization with soluble antigen in vitro. Following adoptive transfer into irradiated mice and repeated stimulation of these mice with antigen, J11dlo cells generated memory responses which were similar to those generated by J11dlo memory cells obtained from primed mice. In contrast, J11dhi B cells from unprimed mice gave rise to both primary and memory responses, but the memory responses were lower than those generated by J11dlo cells. Although the expression of J11d on both J11dhi and J11dlo cells from unprimed mice decreased after adoptive transfer, J11dlo, as compared to J11dhi, virgin cells proliferated more rapidly. These results suggest that memory responses are elaborated predominantly from J11dlo virgin cells. Taken together with previous results, our studies indicate that, J11dlo B cells are different from J11dhi B cells. Hence, they are either memory precursors or are memory cells.