HUMAN TONSIL, BLOOD AND BONE-MARROW IN-VIVO INDUCED B-CELLS CAPABLE OF SPONTANEOUS AND HIGH-RATE IMMUNOGLOBULIN SECRETION IN-VITRO - DIFFERENCES IN THE REQUIREMENTS FOR FACTORS AND FOR ADHERENT AND BONE-MARROWSTROMAL CELLS, AS WELL AS DISTINCTIVE ADHESION MOLECULE EXPRESSION

Human B cells capable of spontaneous IgG secretion are commonly found in circulation and in lymphoid tissues such as tonsil and bone marrow (BM). The present study compares the mechanisms that regulate tonsil, blood and BM B cells capable of spontaneous IgG secretion, The BM cell subset produced IgG during a markedly longer period of time (14 days) than did tonsil and blood cell subsets (2-3 days). Blood and BM, but not tonsil, B cell IgG secretion depended on the presence of adherent cells, as demonstrated by adherent cell depletion and re-addition expe riments. Stromal BM cells supported linear IgG secretion by non-adhere nt BM cells for 2 weeks, but were unable to prolong the short-term IgG secretion by tonsil and blood cells. Different factors induced IgG se cretion in each of the three B cell populations as optimal IgG secreti on by tonsil, blood or BM cell subsets required either tumor necrosis factor-alpha, interleukin-6 or fibronectin + interleukin-6, respective ly. Finally, these populations also showed differences in the expressi on of adhesion molecules; the tonsilar cell subset was PNA(+/-) CD44() CD19d(+) CD19e(-) Leu-8(+/-), the blood cell subset was PNA(-) CD44( +/-) CD49d(+) CD49e(-) Leu-8(+) and the BM cell subset was PNA(-) CD44 (+/-) CD49d(+) CD49e(-) Leu-8(-). These results suggest that the mecha nisms controlling the final differentiation and the expression of adhe sion molecules in these B lymphocytes exhibit territorial specificity.