HUMAN MONOCYTE FUNCTION-TEST - RELEASE OF B-CELL DIFFERENTIATION FACTOR (BDF)

The test described here determines a secretory monocyte function and differs in this respect from existing monocyte function tests; it measures the ability of monocytes to release a factor which induces differentiation of B cells (B-cell differentiation factor, BDF). BDF causes antigen-stimulated B cells to differentiate into antibody-producing cells. BDF released by human monocytes acts across species and can be assayed conveniently in murine spleen cell cultures. BDF is released by human monocytes in response to stimulation with bacterial lipopolysaccharide (LPS). Interference by residual LPS in the BDF preparation can be eliminated using for the assay of BDF-activity spleen cells from a mouse strain that is genetically unresponsive to LPS. An initial survey of some 150 individuals showed considerable variation in BDF production. Cancer patients as a group showed low activity. Low BDF production was also found in patients with aplastic anemia and common variable immune deficiency. © 1979.