Immunological subclassification of non‐T, non‐B acute lymphoblastic leukaemia in childhood

41 cases of non-T, non-B acute lymphoblastic leukaemia (ALL) were classified by immunological criteria using a panel of monoclonal antibodies against common ALL antigen (cALLa), p24, p20 and HLA-DR antigens. Out of 41 cases, cALLa, p24, p20 and HLA-DR antigens were positive in 31 cases, 34 cases, 35 cases and 41 cases, respectively. 4 cases expressing cytoplasmic (i heavy chains were included in the group of common ALL. We demonstrated that a majority of non-T, non-B ALL would be derived from B-lineage cells. The expression of p24 and p20 was followed by the expression of cALLa and the synthesis of cytoplasmic immunoglobulin. These items of evidence support the idea that the expression of cALLa, p24, p20 and HLA-DR antigens on ALL cells would be universal in the USA, Europe and Japan. Although morphologically identical, non-T, non-B ALL cases could be subdivided into phenotypically-defined subgroups on the basis of cALLa, p24, p20 and HLA-DR antigens.