Immunophenotypic characterization of infiltrating polynuclear and mononuclear cells in childhood brain tumors.

During a systematic cell surface antigen expression profile analysis of 76 primary childhood brain tumors (34 medulloblastomas/primitive neuroectodermal tumors and 42 astrocytomas), we employed the following library of monoclonal antibodies (MoABs): anti-Leu-2/a; anti-Leu-3/a; anti-Leu-M5; anti-Leu-11b; anti-HLA-A, -B, -C; anti-HLA-DR; anti-HLe-1 (leukocyte common antigen); and UJ 308. The MoABs identified the expression of various leukocyte-associated, lymphocyte cell line differentiated, cell surface antigens in childhood brain tumors. The antigens were detected with an indirect, biotin-streptavidin-conjugated alkaline phosphatase (AP) immunocytochemical technique. Leu-2/a+ cells comprise the significant CD8+ cytotoxic T-lymphocyte (CTL) population of the tumor-infiltrating lymphocytes. CTLs are major histocompatibility complex (MHC) class I restricted, tumor-associated antigen-specific, cytotoxic cells and were identified in 58 of 76 (76.32%) brain tumors. CTLs usually represented 1-10% of all cells, but in some cases 30-44% of the cells were CD8+. CD4+, MHC class II restricted helper lymphocytes, detected with MoAB anti-Leu-3/a, were present in 65 of 76 (85.53%) brain tumors. Usually 1-10% of the observed cells reacted with MoAB anti-Leu 3/a. Macrophages (Leu-M5 antigen-positive cells) were expressed in 74 of 76 (97.37%) brain tumors. Their number also represented 1-10% of all observed cells in the frozen brain tumor sections. All 76 (100%) brain tumors contained cells that reacted positively with MoABs anti-HLA-A, -B, -C and anti-HLA-DR, demonstrating a strong MHC class I restriction of the tumor cell population and an overall leukocyte antigen expression.(ABSTRACT TRUNCATED AT 250 WORDS)