Interaction between a synthetic analogue of vasopressin and human peripheral blood lymphocytes

The interaction between 1-desamino-8-D-arginine vasopressin (DDAVP) and human peripheral blood lymphocytes was investigated in vitro, using DDAVP concentrations ranging between 1 pg and 10 microgram per ml. DDAVP did not display any mitogenic activity in the absence of phytohaemagglutinin (PHA). Neither did DDAVP have any significant effect on the PHA-stimulated incorporation of 3H-thymidine into DNA, provided that optimally mitogenic concentrations of PHA were present. However, DDAVP either enhanced or inhibited lymphocyte transformation initiated by suboptimally mitogenic concentrations of PHA: the direction of the response depended on the magnitude of the transformation response induced by the PHA alone. Experiments employing 125I-DDAVP demonstrated that DDAVP bound reversibly to untransformed lymphocytes, and that at 20 degrees C, the amount bound increased rapidly to reach a plateau value after 60 minutes. The binding of DDAVP was inhibited in the presence of Pitressin or arginine vasopressin suggesting that human peripheral blood lymphocytes have surface receptors for the vasopressins which also react with DDAVP.