Monoclonal antibodies generated against activated B-cells: unexpected specific reactivity to T-cells

Monoclonal antibodies (Mabs) were produced against C57B1/6 "nude" lymphoblast cells. They are IgG2a and do not react with mouse serum proteins. Five Mabs were characterized functionally by immunohistochemistry and immunofluorescence in spleen, lymph nodes and Peyer's patches from nude and normal mice, and normal mouse thymus. Two Mabs reacted with regions containing B-cells as indicated by immunoperoxidase staining, another recognized T- and B-cell sites and two specifically stained T lymphocyte-containing areas. Immunofluorescence studies confirmed the sites identified above by immunohistochemistry.