Group specific human granulocyte antigens are serologically detectable with granulocytotoxic positive human alloantisera on a cell line, K562, of chronic myelogenous leukemia origin which bears a Philadelphia chromosomal marker. The same cell line lacks serologically detectable HLA, B2 microglobulin, and B [bone marrow-derived]-lymphocyte antigens. Granulocyte antigens are important cell markers for cell lines of suspected myeloid lineage.