Not adhering to a plastic, B-cells of intact or immunized with the suboptimal dose of ram erythrocytes mice were treated in vitro with several agonists and antagonists of cAMP and prostaglandins E and then were transferred to syngenic or allogenic unirradiated recipients. Afterwards the number of the antibody-forming cells against ram erythrocytes was determined. It was shown that a decrease of cAMP and prostaglandin E contents in the intact B-cells results in the appearance of the ability to stimulate the immune response. An increase of cAMP content in the immune B-cells is followed by a reduction of their suppressing activity. The absence of the relationship between this activity and prostaglandin E content in the immune cells is suggested.