Variation amongst K562 cell cultures.

K562 cell cultures were obtained from three laboratories (A, B and C) outside our institution, and were designated according to source as K562A, K562B or K562C. The cultures obtained were constitutive or "wild type" K562 cell cultures, not cloned sublines. These cell cultures were compared with respect to growth kinetics, cell surface protein markers, surface antigens, cytogenetics and hemoglobin production. Morphology, growth kinetics in liquid suspension culture, cloning efficiency in soft agar culture, binding of anti-K562 monoclonal antibodies, and the majority of cell surface proteins were generally similar. In contrast, several important differences were observed: (1) hemoglobin synthesis induced by hemin was significantly different among K562A, B and C, K562A being most sensitive (P less than 0.05); (2) whereas more than 90% of K562A or C cells appeared to be Philadelphia chromosome (Ph1)-positive, less than 15% of K562B cells contained a Ph1; (3) membrane proteins (93 and 85 kilodalton) were identified in K562A, whereas only the 93 kilodalton protein was detected in K562B and neither of the proteins were detected in K562C. Our results indicate that K562 cells maintained in different laboratories can undergo tangible changes which may influence experimental results obtained in studies using these cells.