Cell surface fibronectin on peripheral blood lymphocytes in normal individuals and in patients with acute and chronic lymphocytic leukemia and non Hodgkin's lymphoma.

Fibronectin was detected by immunofluorescence on the surface of one fraction of separated normal peripheral blood lymphocytes using FITC-conjugated anti-human fibronectin antibodies. Approximately one fifth of isolated B cells and 7% of O cells contained surface bound fibronectin but T cells failed to stain. There were no detectable free receptors for fibronectin on the surfaces of the lymphocytes in the different subsets isolated from healthy controls as studied using FITC-labelled purified fibronectin. The per cent of B and O cells bearing surface bound fibronectin was markedly decreased in patients with acute and chronic lymphocytic leukemias and non Hodgkin's lymphoma, only 1-4% of B and 1-2% of O cells stained with FITC-labelled antifibronectin immunoglobulins. FITC-conjugated fibronectin was not bound to the different lymphoblasts isolated from patients with leukemia and lymphoma. Treatment of cells with trypsin and EDTA removed fibronectin bound to the cell surfaces. Fibronectin attached to the surfaces of lymphocytes may have an immunoregulatory function.