Effect of FK506 versus cyclosporine on human natural and antibody-dependent cytotoxicity reactions in vitro

The effect of FK506 and cyclosporine on NK and ADCC activity was evaluated. Cytotoxic cells mediating both activities are resistant to FK506. In contrast, preincubation of ADCC and NK effectors with cyclosporine decreases their cytotoxic potential, while adding the drug to the assays is without effect.

Abnormal B-cell function in hemophiliacs treated with cryoprecipitate and factor VIII and IX concentrates

B-Cell function was evaluated in a group of 43 patients with factor VIII or factor IX deficiency. Thirty had been treated primarily with cryoprecipitate and 13 with concentrates of factor VIII or IX. Serum immunoglobulin G levels were found to be diffusely elevated; however, the absolute number of mature B cells in peripheral blood was normal. B-Cell function as measured by testing mitogen-induced proliferation and and immunoglobulin secretion by plaque-forming cells (PFC) in vitro was reduced. Coculture experiments suggested that these abnormal B-cell responses might be secondary to increased suppressor T-cell activity, which was found more frequently in patients seropositive for antibody to lymphadenopathy-associated virus. Both seronegative and seropositive patients had reduced responses in the proliferative and PFC assays, but the lowest PFC responses occurred in the seropositive group.

Inhibition of human B lymphocyte differentiation by a stable metabolite of cyclophosphamide (ASTA Z 7557, INN mafosfamide)

We have evaluated the immunosuppressive effect of a new stable derivative of cyclophosphamide (ASTA Z 7557) on human lymphocyte immunoglobulin biosynthesis in vitro. When graded amounts of the drug are added to lymphocyte cultures stimulated with the helper T cell-dependent activator (PWM), a marked inhibition of B cell proliferation and differentiation occurs. Lymph node cells are particularly sensitive to the drug, while splenocytes are relatively resistant. The agent exerts only a minor effect on immunoglobulin synthesis triggered by a direct B cell stimulant (S. paratyphi bacteria).