Immune Responses Induced By Intranasal Immunization With IL-2 Plus Soluble Tachyzoite Antigen In BALB/c Mice

Objective To investigate the immune responses induced by intranasal immunization with different doses of IL-2 plus soluble tachyzoite antigen (STAg) and determine the optimal dose of for intranasal immunization in BALB/c mice. Methods Sixty 5-to 6-week-old BALB/c mice were randomly divided into six groups. The mice of experimental groups were immunized intranasally two times at 14-day intervals with 20μg STAg alone, 20μg STAg plus 250IU IL-2, 20μg STAg plus 500IU IL-2, 20μg STAg plus 1000IU IL-2 or 20μg STAg plus 2000IU IL-2. The mice of control group were immunized intranasally with PBS at the same time. To observe the health of mice. All animals were killed on day 30 after the last immunization. Lymphocytes of spleen and intraepithelial lymphocyte (IEL) were counted. The content of IgA antibody in the feces and IgG in the sera were detected by ELISA. Results Proliferative responses were observed in IEL and spleen T lymphocytes , and the T lymphocytes of spleen in the groups of STAg plus 500IU IL-2 and STAg plus 1000IU IL-2 were obviously higher than that of control group and STAg group(P<0.05). The content of IgA antibody (P<0.05)in the feces and IgG (P<0.01)in the sera of the groups of STAg plus 500IU IL-2 and STAg plus 1000IU were obviously higher than that of the control group and STAg group. Conclusions Intranasal immunization of STAg plus 500IU IL-2 was prior to other groups, which not only inspired cellular immune response effectively in mucosal sites, but also stimulated humoral immune responses which produced the higher level of mucosal sIgA and sera IgG antibody.