The cells of human colostrum. II. Synthesis of IgA and Beta1c.

TLDR: IgA produced by the cells of human colostrum may be used in the formation of secretory IgA and may be an important source of antibodies in Colostrum.

Abstract: The immune functions of the cells of human colostrum are further explored by testing the ability of cells to synthesize IgG IgA IgM and Blc. Prepartum and postpartum colostrum samples were collected from 8 volunteer patients by means of a breast pump and subjected to centrifugation. The cells were cultured with carbon-14 labeled amino acids. Radioactive amino acids incorporated into the newly synthesized proteins from the cultures were detected by immunoelectrophoresis and autoradiography. Control experiments were also done: 1) human peripheral leukocytes cultured in radioactive amino acid medium served as positive controls for synthesis of immunoglobulins; 2) normal human serum cell-free human colostrum or colostral cells were subjected to immunoelectrophoresis and 3) protein synthesis was inhibited by adding 300 mcg of puromycin or 2 mcg of actinomycin D to cell cultures. The control experiments showed evidence of in vitro production of IgA IgM and less frequently IgG by human peripheral blood leukocytes. Radioactive cultures of human serum cell-free human colostrum or ruptured colostral cells did not show labeling of immunoglobulin of Betalc precipitatin lines. No radiolabeled immunoprecipitin lines were found with antisera to IgG or IgM but radioactive immunoprecipitin lines were found in some of the anti-Betalc/Betala preparations. Al the anti-IgA preparation showed distinct evenly labeled immunoprecipitin line. When anti SP (secretory piece) was used an immunoprecipitin line was shown corresponding to the anodal portion of secretory IgA. Further experiments should be done to determine if either the secretory type of IgA or the SP is synthesized by cells of human colostrum.