Pharmacological studies on lymphocytes: 2. Effects of indole derivatives and their antagonists on the lymphocyte migration.

The influence of serotonin (5-HT) probably released in reactions of delayed-type hypersensitivity (DTH) on the locomotion of lymphocytes was investigated. 5-HT has a chemokinetic and a chemotactic action on the movement of enriched T-lymphocytes. This 5-HT activity is inhibited by 5-HT antagonists as 2-bromolysergic acid diethylamide, methysergide and pizotiphen. The metabolic product of 5-HT the 5-hydroxyindoleacetic acid has the same activity as 5-HT itself, whereas 5-hydroxytryptophan is without significant influence on the lymphocyte migration. Thus it is supposed that the action of 5-HT on the lymphocyte movement is a specific effect. Lymphocytes are also chemokinetically stimulated by the mediators of the DTH, the lymphokines. 5-HT and lymphokines given together lead to an additive effect. The physiological importance of the described results have to be evidenced for in vivo conditions.