OBJECTIVETo investigate the level of mRNA expression of complement C3 and C4 in rat nasal mucosa and to reveal the relationship with the pathogenesis of allergic rhinitis (AR) .

METHODSTwenty healthy SD rats were randomly divided into AR group and control group, 10 rats for each group. Ten rats was sensitized and intranasally challenged by ovalbumin and Al (OH)3 (as supplement) as allergic rhinitis models, and the control group was treated by saline. RT-PCR was performed to investigate the level of mRNA expression of complement C3 and C4 in nasal mucosa of both groups.

RESULTSC3 and C4 mRNA were detected in both groups. The relative intensity of gene expression was measured. The relative intensity of C3 mRNA expression was 6183+/-1376 in AR group, 4444+/-989 in control group, C4 mRNA was 4398 +/-948 in AR group, and 2771+/-407 in control group. Expression of C3 and C4 in AR group was higher than that of the controls ( P < 0. 05) .

CONCLUSIONThe high level of C3 and C4 mRNA expression in nasal mucosa of rats with allergic rhinitis suggests that C3 and C4 are involved in the immunopathology of allergic rhinitis. The result implies that complement system involved in the rat's allergic rhinitis is possibly activated through the classical pathway.