Presence of NCA (nonspecific cross-reacting antigen) in the cells of the human granulocyte series.

The presence of NCA (nonspecific cross-reacting antigen) in the cells of the human granulocyte series was investigated by using the immunoperoxidase technique. NCA was detected in normal bone marrow at the promyelocyte stage. It was found in leukemic myeloblasts only when they had some degree of differentiation (M2 type), but the results for promyelocytic leukemias (M3 type) were always negative. Auer rods were never stained by anti-NCA serum. In chronic myeloid leukemias, many pathologic myelocytes were positive, their intensity varying from one case to another; a relation was noted between the intensity of this reaction and the number of neutrophil granules stained by Giemsa reagent on parallel slides of the same cases. Normal-looking polymorphs were often weakly labeled or not labeled by anti-NCA serum in the bone marrow or blood of leukemic patients. Here again, a parallel was seen with the staining of neutrophil granules by Giemsa. From these data, an association between NCA and azurophilic granules can be deduced.