Differential diagnosis of malignant lymphoma and nonlymphoid tumors using monoclonal anti-leucocyte antibody.

Pathologic samples from 34 cases of human solid malignancies were tested for reactivity with monoclonal anti-human leucocyte antibody, designated 2D1. This antibody detects a human leucocyte antigen (HLe-I) that is expressed strongly on B and T lymphoid cells and weakly on early hemopoietic cells, but is not found on normal mesenchymal and epithelial tissues. This study demonstrates the use of this reagent in cryostat sections of tumor samples using indirect immunofluorescence in combination with other lymphoid markers such as anti-T cell serum, anti-Ia-like serum (detecting p28, 33 "B cell associated" membrane antigen) and antisera to different immunoglobulin isotypes. Tumor cells from all 12 cases of epithelial malignancies and sarcomas were HLe-I- although adjacent (normal) lymphoid cells showed strong positive staining. In contrast, 20 cases of lymphoma (B- as well as T-cell types) were HLe-I+. Two other malignancies involving the lymphoid system were HLe-I- and failed to express any of the other lymphoid markers tested.