Characteristics of immune function of full-term infants with different feeding patterns at the age of 3 months: a prospective cohort study

Objectives: To explore the characteristics of immune function of healthy full-term infants at the age of 3 months, and to analyze the relationship of immune function with feeding pattern and sex.

Methods: A total of 84 healthy full-term infants born in four hospitals in Beijing and Hohhot, China were prospectively recruited. Their feeding patterns remained unchanged within 4 months after birth. They were divided into a breast-feeding group and a milk powder feeding group according to their feeding patterns. At the age of 3 months after birth, peripheral venous blood samples of the two groups were collected to evaluate cellular immunity and humoral immunity and perform routine blood test. The laboratory indices were compared between infants with different feeding patterns and sexes.

Results: Compared with the milk powder feeding group, the breast-feeding group had significantly lower proportion of T cell second signal receptor CD28, immunoglobulin M, and proportion and absolute count of neutrophils (P<0.05) and significantly higher expression and proportion of HLA-DR, a surface activation marker of CD8⁺ T cells, and proportion of lymphocytes (P<0.05). The male infants had a significantly lower white blood cell count and a significantly higher proportion of eosinophils compared with the female infants (P<0.05).

Conclusions: Sex has no significant effect on the proportion of lymphocyte subsets in 3-month-old full-term infants, but feeding patterns are associated with the proportion of CD28⁺ T cells (lymphocyte functional subset) and HLA-DR⁺ T cells (lymphocyte activation subset), suggesting that feeding patterns have a certain effect on the development of immune function in 3-month-old full-term infants.