Replicative properties of lipopolysaccharide-induced murine B lymphocytes: detection of three different responses to...

A number of investigators have reached different conclusions regarding the proliferative behavior of murine B lymphocytes stimulated by lipopolysaccharide (LPS). We examined the replicative properties of LPS-stimulated splenic B cells in primary culture using a density transfer technique to detect DNA replication. The method selectively monitors those lymphocytes that synthesized DNA in a first division and determines whether their progeny undergo subsequent replication, providing information about the growth characteristics of the first generation of LPS-responsive cels. Three different proliferative responses were observed. In one type, the initial signal that stimulated parental cells to divide was perpetuated in their progeny in that daughter cell proliferation occurred in the absence of mitogen (19 to 37% of the parental cells, mode I). In another type of response, the proliferation of daughter cells depended on further exposure to mitogen (10 to 17% of the parental cells, mode II). In a third response, proliferation of daughter cells did not occur even in the presence of mitogen (54 to 64% of the parental cells, mode III). Three types of growth responses were also observed for Con A-stimulated T cells. A larger proportion of T cells, however, were restimulated to an additional round of DNA replication (40 to 55% of the cells, mode II) when compared to LPS-stimulated B cells. These in vitro growth responses suggest alternate pathways by which antigens may regulate immune reactions.