Popliteal lymph node enlargement and antibody production in the mouse induced by drugs affecting monoamine levels in the brain.

Drugs that affect monoamine levels in the brain were screened for their potential to cause immunological changes in the popliteal lymph node (PLN) of mice after injection into the hind paw. The tricyclic antidepressant (TCA) drugs, imipramine and amitriptyline, and the serotonin reuptake blocker, zimeldine, induced a prominent PLN weight gain in C57BL/6 mice. Ketanserin and ritanserin appeared less effective while nomifensine, serotonin and the antigen, sheep erythrocytes, lacked significant activity. In BALB/c mice all agents induced an increase of PLN cell number, the TCA drugs and zimeldine appeared superior in this respect. Increased IgM as well as IgG production on a per cell basis was only induced by the TCA drugs, zimeldine and, especially, sheep erythrocytes. Data indicate that induction of PLN responses is not a general property of agents affecting monoamine levels. Structural, i.e. antigenic, characteristics of the drugs rather than their pharmacological properties are probably at play.