Abstract: Objective To investigate the kinetics of IgA secreting cells （IgASCs） in small intestine and the specific antibody level induced by Toxoplasma gondii tachyzoite infection in mice. Methods Ninety-six BALB/c mice were randomly divided into 2 groups, 12 were intragastrically given 0.5 ml PBS as control, the rest were each intragastri-cally infected with 1×104 tachyzoites of the virulent RH strain Toxoplasma gondii. On the day 2, 4, 6, 8, 10, 12, and 14 post infection, 12 mice were sacrificed respectively. The quantity of IgASCs in mucosa of duodenum, jejunum and ileum was detected by immunohistochemistry analysis. IgA in sera and in intestinal washes was determined by ELISA. Results The IgASCs were found in lamina propria of the small intestine mucosa. The amount of IgASCs in duodenal mucosa inc-reased gradually with the time after infection, while in jejunal mucous membrane it increased from the day 2 to 8, and then decreased to the level of before infection on day 14. The amount of IgASCs in ileal mucous membrane also increased from day 2 to 6, then descended gradually and on the day 12 to a level lower than that of before infection. IgA level in the intestinal washes increased continually but there was no significant change in serum samples. The correlation between IgA level in intestinal washes and the quantitative change of IgASCs in mucosa of duodenum, jejunum and ileum was r=0.732 （P＜0.01）, r=0.116 （P＞0.05） and r=-0.429 （P＜0.01）, respectively. Conclusion Toxoplasma gondii infection induces a high level expression of IgASCs in duodenum and an increase of IgA antibody in the intestinal washes, showing a positive correlation. The high level IgA in the intestinal washes is mainly from IgASCs of the duodenal mucosa.

Key words: Toxoplasma gondii, Antibody secreting cell, IgA, Mucosal immunity