REDUCED RESPONSIVENESS OF IMMATURE B-CELLS TO THE B-CELL MITOGEN, LIPOPROTEIN

When pre-B [bone marrow-derived] cells are isolated from [mouse] bone marrow and incubated in vitro for several days, they spontaneously differentiate into LPS[lipopolysaccharide]-reactive B cells. These newly produced B cells do not respond to another B cell mitogen, lipoprotein (Lp). The lack of Lp reactivity of newly produced B cells represents a qualitative difference between these cells and B cells in peripheral tissues that respond equally well to LPS and Lp. Responsiveness to different mitogen provides unique markers to identify B cells at early stages of development.