Abstract: Infant formula is one of the major infant formula products currently available on the market. In this experimental study, the effect of pasteurized infant formula on T cell subsets and serum immune factors in rats was explored. Healthy SD male rats were divided into 4 ?dietary treatment?groups including basal diet, commercial normal temperature infant formulas I and II, and pasteurized infant formula. Body mass, the serum levels of interleukin (IL)-2, IL-4, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and lysozyme, and the relative contents of CD3+, CD4+ and CD8+ lymphocytes and CD4+/CD8+ ratio in whole blood were measured. The body mass of rats administered with the three infant formulas was significantly higher than that of rats in the basal diet group (P < 0.05). The serum levels of IL-2, TNF-α and lysozyme in the pasteurized infant formula group were significantly higher than those in the other infant formula groups (P < 0.05), and the IFN-γ level was significantly higher than that in the basal diet group (P < 0.05) but was not significantly different from that in the other infant formula groups. The serum levels of IL-4 in the three experimental groups decreased to different extents with administration time, but they were significantly higher than that in the basal diet group (P < 0.05). The relative contents of CD3+, CD4+ and CD8+ lymphocytes in the whole blood of rats given pasteurized infant formula were (34.90 ± 1.15)%, (23.93 ± 2.11)%, and (9.17 ± 0.42)%, respectively. These results showed that pasteurized infant formula promoted the growth of SD rats and the proliferation and differentiation of lymphocytes, enhanced humoral immunity and cellular immune function, and improved immune regulation in rats when compared with commercial infant formula.

Key words: pasteurized infant formula, T cell subsets, blood immune factors