title: Phagocytosis of the streptococcal preparation OK-432 (picibanil) by non-phagocytic human leukemia K 562 cells and its modulation by tumor cell differentiation.
abstract: OK-432, an inactivated and lyophilized preparation of a low-virulence strain of Streptococcus pyogenes induced a phagocytosis process in human erythroleukemic K 562 cells. This process seems to be specific to the cell line, known however as non-phagocytic, and specific to the bacterial preparation. Transmission and scanning electron microscopy confirmed phagocytosis. Increased lysosomal activity was also demonstrated by cytochemical and biochemical criteria. The induction of phagocytosis required an intact cell surface membrane and sialo-glycoproteins seemed to be implied. The phagocytosis was inversely correlated with the erythroid differentiation of the K 562 cell. Hemin-treated K 562 cells and the markedly erythroid K 562 clone showed a decreased level of phagocytosis. The phagocytosis level in a K 562 clone expressing Fc (IgG) receptors was not altered by OK-432. In addition, a weak erythroid K 562 clone expresses the same level of phagocytosis as the total population.
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000818:Animals; D001688:Biological Products / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D006801:Humans; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D007939:Leukemia L1210 / Q000378:metabolism; D010587:Phagocytosis; D010844:Picibanil / Q000378:metabolism* / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D001688:Biological Products; D010844:Picibanil; D000135:Acid Phosphatase; D014357:Trypsin