Characterisation of breast cancer infiltrates using monoclonal antibodies to human leucocyte antigens.

Serial frozen sections from eleven patients with malignant breast tumours and five patients with benign disease were studied by indirect immunoperoxidase using a panel of mouse monoclonal antibodies to human leucocyte antigens. More infiltrating leucocytes were seen in tumour sections than those of benign conditions. A considerable proportion of the infiltrating cells were T cells, and more of these were of the suppressor/cytotoxic subset than the helper/inducer subset. The T cells were apparently not all activated as indicated by lower levels of staining with anti HLA-DR than anti-leucocyte antibody. Diffuse staining was sometimes seen with HLA-DR and T cell subset antibodies. Tumour cells did not stain or were only very weakly positive with anti HLA-A, B, C.