The purpose of this project is to analyze the cellular control of immune function in normal individuals and in certain patients with neoplastic disease. We are currently determining the helper and suppressor activity of neoplastic T cells from patients with acute lymphoblastic leukemia and cutaneous T-cell lymphomas. We are also studying abnormalities of regulatory monocytes and T-cells from patients with multiple myeloma and mice bearing plasmacytomas. Finally, we are characterizing the capacity of antibodies directed against surface membrane products of immune respone genes to inhibit human immune reactions by activating regulatory T cells.