DESENSITIZATION OF HUMAN-PLATELETS BY PLATELET ACTIVATING FACTOR

Human platelets are less responsive to PAF [platelet-activating factor] at 37.degree. than at 25.degree. C. They can be desensitized to the effects of PAF by preexposure to small concentrations. In both cases, desensitization appears to be accompanied by a decreased affinity of the high affinity site for PAF, rather than by loss of binding sites. Alteration of a metabolic step subsequent to binding cannot be excluded, but platelets show normal response to a variety of other agents under the conditions resulting in desensitization of platelets to PAF.