Effect comparison of two adjuvants in the preparation of rat CIA model

ObjectiveTo compare the effects of incomplete Freund′s adjuvant(IFA) and complete Freund′s adjuvant(CFA) combined with calf Ⅱ collagen(CⅡ) in establishing the collagen-induced rheumatoid arthritis(CIA) rat model.

MethodsThirty SD rats aged 8 weeks were randomly divided into the 0.9% sodium chloride solution group(control group), IFA+CⅡ group and CFA+CⅡ group(10 rats in each group).The IFA/CFA and CⅡ were blerding in equal volume, and intradermally injected into the root of rat tail.The 200 μL and 100 μL mixture were injected into rats in the model group on day 0 and day 7, respectively.The same volume of 0.9% sodium chloride solution was injected into rats in the control group using the same method.The scores of arthritis index(AI) in three groups were recorded every 7 days from the initial immunization.HE staining was performed in ankle joints of 5 rats from three groups on day 14 to observe the pathological changes.

ResultsOn day 0 and day 7 after modeling, the AI values in three groups were 0.On day 14 after initial immunization, the AI values in IFA+CⅡ group and CFA+CⅡ group were(6.5±0.5) and(7.4±0.4), respectively, and the difference of which was statistically significant(P < 0.01).On day 21 after modeling, the AI values in IFA+CⅡ group and CFA+CⅡ group were(8.8±0.5) and(7.8±0.8), respectively, and the difference of which was statistically significant(P < 0.01).But the difference of AI values in IFA+CⅡ group and CFA+CⅡ group were not statistically significant on day 14 and day 21 after modeling(P>0.05).The results of HE staining of the ankle joint showed that the cartilage surface in ankle joint in the IFA+CⅡ group was rough and slightly damaged, and inflammatory cell infiltration was observed in the articular cavity.In CFA+CⅡ group, the articular cartilage was obviously damaged, presented saw tooth shape, and had obvious pannus and a large amount of inflammatory cell infiltration.

ConclusionsBoth IFA+CⅡ and CFA+CⅡ can be used to prepare RA model, and the inflammatory response of IFA+CⅡ is slight, which is the preferred method for preparing RA model.