母乳喂养婴儿的发病率与死亡率均较牛奶喂养者低,已为临床观察与动物实验所证实。人乳的这种免疫作用,己知与乳汁中分泌型免疫球蛋白A(SIgA)、补体及溶菌酶等体液因素有关,乳汁中吞噬细胞也可能是乳汁抗感染作用另一重要细胞因素。动物实验初步证明,乳汁吞噬细胞有较强的吞噬与杀菌作用。 The morbidity and mortality of breastfeeding infants are lower than that of milk-fed infants, which has been confirmed by clinical observation and animal experiments. This immunosuppression of human milk is known to be associated with humoral factors such as secreted immunoglobulin A (SIgA), complement and lysozyme in milk, and phagocytic cells in milk may be another important cytokine for the anti-infective effect of milk. Animal experiments initially proved that milk phagocytic cells have a strong phagocytosis and bactericidal effect.