Distribution of surface nonspecific cross-reacting antigen and influence of proteolytic enzymes on this antigen in myeloid cell series.

Discontinuous density-gradient centrifugation was used to separate myeloid cells of different myelocytic leukemias [acute myelocytic leukemia (AML), chronic granulocytic leukemia (CGL), and chronic granulocytic leukemia in blast crisis (CGL-BC)] into fractions containing granulocytes in individual stages of maturation. The distribution of surface nonspecific cross reacting antigen (sNCA), and cytoplasmic NCA (cNCA) in each cell fraction was estimated by immunofluorescence (IF), and the influence of proteolytic enzymes and neuraminidase on sNCA presence was analyzed. It was found that the percentage of sNCA- and cNCA-positive cells increased in more mature granulocyte fractions; only in the morphologically oldest granulocytes did the number of sNCA-positive cells decrease, probably as a result of the rise of NCA secretion into body fluids; proteolytic enzymes caused an increasing number of sNCA-expressing cells; and neuraminidase treatment usually reduced the percentage of sNCA-positive cells.