Pharmacological control of the hormonally modulated immune response. II. Blockade of antibody production by a combination of drugs acting on neuroendocrine functions. Its prevention by gonadotropins and corticotrophin.

Injection of a combination of three drugs, 5-hydroxytryptophan, the alpha-blocker phentolamine and the neuroleptic drug haloperidol into mice before or together with sheep red blood cells (SRBC) induces a complete and long-lasting inhibition of antibody production to SRBC and leads to specific unresponsiveness. The mice unresponsive to SRBC respond normally to another antigen. Treatment with a combination of luteotropic (LH), follicle stimulating (FSH) and corticotropic hormone (ACTH) before administration of drugs and antigen prevents the immune blockade. Injection of SRBC induces an early elevation of LH in blood. This effect is prevented by previous administration of the three drugs in combination. The hormonal response to a second injection of the same antigen of mice previously made 'unresponsive' is different from that of immunized animals. The suppression of these hormonal changes which follow antigen injection by drugs acting on neuroendocrine regulation and cell membrane adrenergic receptors represents a step forward in efforts aimed at a pharmacological control of acquired immunity.