Prolonged effect of an H1-receptor blocker antihistamine on the histamine content of white blood cells and mast cells

Hormonal imprinting usually takes place perinatally at the first encounter between the developing receptor and its target hormone, determining the future binding capacity of the receptor for life. Molecules similar to a hormone can cause faulty imprinting also with life-long consequences. Hormone production of the imprinted cell is also durably influenced. In cytogenic organs imprinting can also be provoked in adulthood. At present the effect of a single terfenadine treatment in adult rats on the histamine content of peritoneal cells (lymphocytes, mast cells and the monocyte-macrophage-granulocyte group), white blood cells (lymphocytes, granulocytes, monocytes) and thymic lymphocytes was studied 3 weeks after treatment to clarify the effect of prolonged treatment with an antihistamine in adulthood. The cells were studied by flow cytometric analysis. Peritoneal mast cells contained significantly more and thymic lymphocytes significantly less histamine than controls. In the Other cells the differences were not significant. The results support earlier observations on the effect of antihistamines on mast cell histamine release (inhibition) and call attention to the fact that this effect is durable (hormonal imprinting provoked in adults).