The effect of colostrum and colostral antibody SIgA on the physico-chemical properties and phagocytosis of Escherichia coli o86.

A hydrophilic effect of human colostrum and colostral antibody SIgA binding on Escherichia coli o86 has been demonstrated by hydrophobic interaction chromatography on Octyl-Sepharose and partition in a polymer two-phase system containing dextran, poly(ethyleneglycol) and poly(ethyleneglycol)-palmitate. Furthermore, antibody SIgA binding reduced the negative surface charge of the E. coli bacteria. The reaction between centrifuged but not further purified colostrum and bacteria yielded a complex which, compared to bacteria alone, showed decreased negative and increased positive surface charges, the latter being sensitive to pepsin. Binding of SIgA or colostrum to E. coli showed no definite effect on the attachment to and phagocytosis by polymorphonuclear cells in vitro. The effects observed are discussed in relation to the structure of SIgA.