Mouse myeloid leukemia cells can be induced to differentiate into macrophages in vitro by la,25-dihydroxyvi. tamin D3, the active form of vitamin D3. The minimal concentration of la,25-dihydroxyvitamin D3 to induce the cell differentiation was 0.12 nM. The degree of cell differentiation in various markers induced by 12 nM la,25-dihydroxyvitamin D3 was nearly equivalent to that induced by 1 ,M dexamethasone, the most potent known stimulator. Among several markers of the differentiation by la,25-dihydroxyvitamin D3, phagocytic activity was induced within 24 hr, and this was followed by induction oflysozyme and locomotive activities. Similar changes were also induced by 0.01-1 ,uM la-hydroxyvitamin D3. 25-Hydroxyvitamin D3 and 24R,25-dihydroxyvitamin D.3 showed only weak inducing activity. These results suggest the possibility that, in addition to its wellknown biological activities in enhancing intestinal calcium transport and bone mineral mobilization, la,25-dihydroxyvitamin D3 is involved in the differentiation of bone marrow cells.The myeloid leukemia cell line (Ml), originally established by Ichikawa (1) from an SL mouse with myeloid leukemia, is known to differentiate into mature macrophages and granulocytes in vitro when treated with conditioned media from various cell cultures (2), ascitic fluid of tumor-bearing animals (3), bacterial lipopolysaccharides (4), polyribonucleotides (5), or glucocorticoids (6, 7). Among various inducers, dexamethasone has been found to be the most potent stimulator (8). The differentiation can be detected by changes in cell morphology, adhesion ofcells to the dish surface, increase in lysosomal enzyme activity, induction of phagocytic and locomotive activities, and the appearance of Fc and C3 receptors on the cell surface (2-8).It C02/95% air in Eagle's minimal essential medium supplemented with twice the normal concentrations ofamino acids and vitamins and 10% heat-inactivated calf serum (Chiba Serum Institute, Chiba, Japan). The cells were transferred every 2 to 3 days. Except for the study of cell fractionation, all cells (both adherent and nonadherent) were used for determining parameters of differentiation.Hormone and Vitamin D Derivatives. Dexamethasone was purchased from Sigma and 25(OH)D3 was from Philips-Duphar (Amsterdam). la,25(OH)2D3, 24R,25(OH)2D3, and la-hydroxyvitamin D3 [la(OH)D3] were kindly donated by I. Matsunaga, Chugai Pharmaceutical, Tokyo.Fractionation of the Cells by Discontinuous Density Gradient Centrifugation. For the study of cell fractionation, only adherent cells were used in the cultures treated with dexamethasone, la,25(OH)2D3, or la(OH)D3 whereas all cells were used in the control culture. After the nonadherent cells and loosely adherent cells had been removed by gently rinsing three times with prewarmed culture medium, the cells attached to dishes were collected as adherent cells by pipetting with phosphate-buffered saline lacking Ca2+ and Mg2-(PJNaCl) on ice. Determination of Lysozyme Activity. Lysozyme activity was determined by a mo...

Cerebrospinal fluid (CSF), serum and seminal plasma contain a small amount of SP-40,40, a modulatory protein of the human complement system. The SP-40,40 in each body fluid was different in molecular size on SDS-PAGE, and glioblastoma cells, hepatoma cells and testicular tumor cells produced SP-40,40, while neuroblastoma cells did not. Therefore, it was estimated that CSF SP-40,40 originated in glia cells, serum SP-40,40 in liver cells and seminal plasma SP-40,40 in testicular cells. SP-40,40 concentrations in CSF of the patients with Alzheimer's disease and the patients with cerebral tumor were higher than those of normal donors. beta-Amyloid deposits in the brains of the patients with Alzheimer's disease were stained with an anti-SP-40,40 monoclonal antibody (mAb) but not with an anti-S-protein mAb, while cellular processes around beta-amyloid were stained with an anti-S-protein mAb but not with an anti-SP-40,40 mAb. Therefore, beta-amyloid contained SP-40,40 in a form different from that in the soluble membrane attack complex (SMAC, SC5b-9) of the complement, which contains S-protein as well as SP-40,40.

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