Objective To investigate the changes of serum immunoglobulin IgG in peripheral blood of infants aged 0-6 months,and to compare the effects of breast feeding and artificial feeding on the immune function of infants. Methods A total of 90 neonates born from January 2016 to December 2016 were divided into three groups: breast feeding group, mixed feeding group and artificial feeding group. There were 30 newborns in each group.Peripheral blood samples were collected at postnatal 1 d,3 d,7 d, 14 d, 42 d, 3 months and 6 months respectively. Serum levels of IgG were determined by radioimmunoassay, and the contents of each group were compared. T lymphocyte subsets(CD3+, CD4+, CD8+)in peripheral blood at postnatal 6 months were detected. Results The content of IgG in serum of neonatal decreased gradually with the increase of postnatal days.The serum IgG content at postnatal 14 d in the breast feeding group, the mixed feeding group and the artificial feeding group was (95.14 ± 4.55), (90.89±4.35),(91.74±4.19)mg/L respectively,and the breast feeding group was significantly higher than the other two groups,the difference among the groups was statistically significant(F=7.965,P<0.05).The CD8+T lymphocyte cells in the breast feeding group, the mixed feeding group and the artificial feeding group was 0.389 4±0.060 1,0.294 2±0.062 6,0.308 4±0.071 6 respectively,and the breast feeding group was significantly higher than the mixed feeding group and the artificial feeding group,and the difference among the groups was statistically significant(F=4.941,P<0.05).Conclusions Breast feeding can reduce the serum IgG content of infant consumption,slowing the pace of decline,effectively improve the infant's own ability to synthesize IgG,so as to improve infant immunity,promote their healthy growth,it is worthy of clinical application.

Background: Recombination activating gene2 (Rag2) knockout (KO) mice are used widely in various research fields, including vaccine development, transplantation studies, and hematopoiesis research, but few studies have compared their phenotypes. This study examined whether there were differences in the immunophenotypes between Rag2 KO mice derived from different sources. In particular, the changes in the organ weight, histological structure, and subpopulation of T and B cells were compared in the spleen and thymus of C57BL/6-Rag2em1hwl/Korl (Rag2/Korl KO) and B6.Cg-Rag2tm1.1Cgn/J (Rag2/J KO) mice. Results: The weight of the spleen and thymus similarly decreased in the Rag2/Korl and Rag2/J KO mice compared to their wild type (WT) mice, even though the other organs were kept at the same weight. A slight difference between the Rag2/Korl and Rag2/J KO group were detected in the number of white blood cells (WBC), lymphocytes (LYM), red cell distribution width (RDW), and platelets (PLT). In addition, the white pulp of the spleen and the cortex region of the thymus decreased in both Rag2 KO mice compared to WT mice. On the other hand, significant differences in the number of CD8+ T and B cell subpopulations between WT and Rag2 KO mice were observed between Rag2/Korl and Rag2/J KO group, while the CD4+ T subpopulation was maintained similarly in both groups. Conclusions These results suggest that Rag2/Korl and Rag2/J KO mice exhibit similar immunophenotypes in the spleen and thymus except for the differences in the number of CD8+ T and B cell subpopulations.