Immunological Properties of Hematopoietic Malignancies in Childhood

Childhood non-Hodgkin’s lymphomas were immunohistochemically analyzed utilizing monoclonal antibodies. Eighty-two cases were studied and 98% cases were histologically subtyped into lymphoblastic (LB,39%), Burkitt’s lymphoma (BL,31%), and large cell (LA,28%) types. BLs were all positive for pan B markers (immunoglobulins and CD 19/20/22), as well as the activated B-cell antigens, CD 10 and B5. However, BLs were phenotypically heterogenous with the combination of L30 and L29, which detect resting and activated B cells, respectively. With L30 and L29, BLs were subgrouped into three phenotypes (L30+L29−, L30+L29+, and L30−L29+). Study on the distribution of these antigens on normal B cells, as well as on in vitro activation, revealed that the heterogenous antigen expression of BLs corresponds to the dynamic phenotypic change during early activation of mature B cells. Therefore, it is likely that BLs are tumors of early activated B cells. In LAs, 14 anaplastic large cell lymphomas (Ki-1 lymphoma) were included. Phenotypically, Ki-1(CD30), epithelial membrane antigen (EMA), HLA-DR, and the IL-2 receptor were frequently identified. The tumor cells expressed no specific T— cell (CD3/5/8) or B-cell (CD19/20) markers, but coexpression of CD4 and alpha-1-antitrypsin was frequently seen. The results indicate that Ki-1 lymphoma is a heterogenous group of tumors including those of non-lymphoid cell origin.