ABSTRACT
Human colostrum and milk collected at different times during the first six months of lactation from 301 subjects were tested for the levels of SIgA, IgM, IgG, C3, C4, lactoferrin and lysozyme by the technique of radial immunodiffusion. These kinds of immunoglobulins in colostrum and milk were detected, however the SIgA was highest among immunoglobulins in colostrum, which acounted for 89.8%.The average level of SigA on the first day of postpartum was 3152.5 mg/dl and exceeded those in the serum by 13-fold. It was suggested that breast-feeding may be crucial for the newborns before their mucosal immune system has been established. The average levels of C3 and C4 on the first day of postpartum were 99.7mg/dl and 65.9mg/dl respectively, reaching the normal serum level. Lactoferrin was as high as 1228.7mg/dl in the colostrum of the first day of lactation. The concentration of lysozyme was 944.2ug/ml on the first day of postpartum, which was about 429 times higher than that of cow milk. Using Holder pasteurization (62.5℃, 30 minutes), the SIgA and lysozyme activity of the milk could be reduced by 29.7% and 8.3% respectively, but a lot of anti-infective factors still remained in milk. So pasteurization may be useful for the sterilization of stored human milk.