Effects of carrageenan-a macrophage toxic agent-on antibody synthesis and on delayed hypersensitivity in the guinea pig.

Delayed hypersensitivity reactions to the carrier and antibody mediated reactions to the carrier and to the hapten have been studied in guinea pigs treated with carrageenan, a macrophage toxic agent, before or after immunization with a hapten-carrier complex. The results show that carrageenan which acted at the afferent limb of immunity neither depressed nor enhanced delayed hypersensitivity reactions but could affect antibody formation. Macrophage functions in antibody synthesis appeared to be more sensitive to carrageenan than those involved in the induction of cell-mediated immunity. Carrageenan could provide a useful tool for studying the functional heterogeneity of macrophages during the induction of the immune response.