Properties of the K562 cell line, derived from a patient with chronic myeloid leukemia

The K562 cell line derived from a CML patient in blast crisis was examined for properties of B and T lymphocytes and cell lines. K562 lacks the B markers of immunoglobulin, Epstein‐Barr virus (EBV) genome and associated nuclear antigen, and receptors for EBV. A low proportion of cells form rosettes with sheep erythrocytes, the frequency of which is considerably increased after neuraminidase treatment. Unlike B lines but like T lines, K562 cells are lysed rapidly by C'/Fc receptor‐positive human blood leukocytes and do not stimulate MLC reactions. On the other hand, K562 lacks T antigen, high radiosensitivity and sensitivity to growth inhibition by thymidine. The cells do not contain N‐APase, an enzyme found in all lines derived from lymphoid cells and in lymphoproliferative diseases. By scanning electron microscopy, K562 cells were seen to be rounded and relatively smooth, with small numbers of short microvilli resembling undifferentiated leukemic cells. A few cells had narrow ridge‐like profiles and small ruffles similar to granulocytic leukemic cells. K562 is strongly positive for immunoglobulin Fc receptors and pinocytosis, but does not phagocytose or mediate antibody‐dependent phagocytosis or cytolysis. Among histochemical stains, K562 is positive for esterase, lipid, and acid phosphatase. There seems to be no doubt that K562 is not a B cell line. While it has some T cell properties, these are not exclusive. Some of its characteristics indicate that it is probably not lymphoid. Due to its low level of differentiation, its nature cannot be stated with certainty. On the basis of the possible presence of the cellular marker of chronic myeloid leukemia, the Ph chromosome, it may be regarded as belonging to the granulocytic series of cells. Proprétés de la lignée k562, qui provient d'un sujet atteint de leucémie myéǐotde chronique La lignée K562, qui provient d'un sujet atteint de CML en crise blastique, a été étudée du point de vue des propriétis des lymphocytes B et T et d'autres lignées cellulaires. Elk ne posséde ni les marqueurs B de I'immunoglobuline, ni le génome du virus d'Epstein‐Barr (EBV), ni l'antigéne nucliaire qui h i est assocéi, ni les récepteurs de I'EB V. Une faible proportion des cellules forment avec les érythrocytes de mouton des rosettes dont la fréquence s'accrǐt considerablement aprds traitement a la neuraminidase. A la difkrence des lignées Bmais comme les ligntes T, les cellules K562 sont lysies rapidement par les leucocytes du san