HISTAMINERGIC REGULATION OF NK-CELLS - PROTECTION AGAINST MONOCYTE-INDUCED APOPTOSIS

Human natural killer (NK) cells with CD3(-)/56(+) phenotype) acquired features characteristic of apoptosis after incubation with autologous monocytes, as revealed by apoptotic nuclear morphology and degradation of DNA into oligonucleosomal fragments. The monocyte-induced apoptosi s in NK-cells was prevented by the biogenic amine histamine at concent rations exceeding 0.1 mu M. The protective effect of histamine was blo cked by the H-2-receptor (H(2)R) antagonist ranitidine but not by AH20 2399 A, a chemical control to ranitidine devoid of H(2)R affinity. It is concluded that histaminergic mechanisms may serve to protect NK cel ls from damage inflicted by products of the oxidative metabolism of mo nocytes.