Immune effector cells induced by complete Freund's adjuvant exert an inhibitory effect on antigen-specific type 2 T helper responses.

BACKGROUND: It has been well documented that environmental factors such as antigenpresenting cells and related cytokines could affect the development of T helper cells.

OBJECTIVE: The purpose of this study is to investigate the effect of different adjuvants on T cell development.

METHODS: Ovalbumin (OVA) combined with aluminum hydroxide (Alum) plus pertussis toxin (PT) or complete Freund's adjuvant (CFA) were used to sensitize mice; the production of IgG and IgE anti-OVA antibodies was then followed. In addition, OVA-specific proliferative responses and cytokine production by spleen cells were also investigated.

RESULTS: The data showed that the adjuvants themselves could modify the pattern of immune response: (1) IgG2a anti-OVA antibody was higher in mice sensitized with OVA + CFA compared to that of mice sensitized with OVA + Alum + PT; (2) the ratio of IFN-gamma/IL-4 produced by OVA-stimulated spleen cells was higher in mice sensitized with OVA + CFA than that of mice sensitized with OVA + Alum + PT: (3) increased percentage of gamma delta T cells was noted in the peritoneal exudate cells of OVA + CFA immunized mice; and (4) the immune response of mice sensitized with OVA + Alum + PT was inhibited by the adoptively transferred ascitic cells from OVA + CFA immunized mice.

CONCLUSION: In general, the data suggested higher IgG2a and the ratio of IFN-gamma/IL-4 was noted in mice sensitized with OVA + CFA. Further elucidation of the regulatory mechanism of allergen-specific T helper cells development and exploration of possible agents for immunotherapy might shed light on the management of atopic diseases.