The proinflammatory function of lymphocytes in non-immune inflammation: effect of steroidal and non-steroidal anti-inflammatory agents.

Leucopenia rendered rats unresponsive to various inflammatory stimuli. The intensity of the inflammatory response in such animals was restored by i.v. administration of suspensions of lymphocytes, but not of granulocytes. This restorative effect was blocked by both steroidal and non-steroidal anti-inflammatory drugs. Utilizing carrageenin to induce inflammatory responses in the rat's paw, the effect of these drugs on lymphocytes was observed in two circumstances. First, following incubation of the cells with the drugs in concentrations not exceeding the peak plasma levels estimated for these substances in man or laboratory animals; the effect of the drugs seemed selective, since anti-histamine and anti-serotonin agents, as well as amethopterin, were devoid of action. Second, when lymphocytes were collected from rats previously treated with the various anti-inflammatory agents, injected 6-hourly during periods of 18 and 36 h, respectively, for steroidal and non-steroidal anti-inflammatory substances. The total amounts given were lower than those required to produce consistent anti-inflammatory effects in normal animals, when the drug was given as a single dose before injection of the irritant. It is concluded that the pro-inflammatory function of lymphocytes in non-immune inflammation can be blocked by steroidal and non-steroidal anti-inflammatory agents.