[Role of cyclic nucleotides in the immunomodulating action of histamine in mice]

A study was made of histamine action on different lymphocyte subpopulations of the mouse spleen during sensitization with ovalbumin. Histamine was shown to exert a regulatory action on proliferation of but rapidly depositing fraction of spleen lymphocytes, which corresponds with suppressor T lymphocytes. The line and intensity of histamine action depended on the time of sensitization. In the initial period histamine reduced the proliferation rate, while on day 3 it stimulated the incorporation of labeled thymidine. The action of histamine was realized through the H2-histamine receptors and was mediated by the increased concentration of cAMP in the lymphocytes.