[Effect of endogenous opioid peptides on antibody formation in the primary immune response to sheep erythrocytes].

The effects of leu-enkephalin and met-enkephalin on the number of the antibody-forming cells (AFC) in the mouse spleen at the primary immune response to ram erythrocytes depending on the dose and time of the agent administration with relation to the time of immunization were studied. The data indicating diverse effects of these endogenous opioid peptides on antibody genesis were obtained. When administered before immunization, met-enkephalin increased the number of AFC in the CBA mouse spleen and its administration simultaneously with an antigen and afterwards decreased the number of AFC. Leu-enkephalin both decreased and increased the number of AFC in the spleen in the dose-dependent way. The stimulating effect of this agent was more pronounced in the C57BL/6 mice with the initially low immune response as compared to the CBA mice.