Antigen-Driven Immunoglobulin Production by Human Colostral Lymphocytes

Abstract

ABSTRACT. It has long been recognized that human milk contains substantial quantities of secretory IgA which is elaborated by plasma cells located proximal to the ductal epithelium. The presence of lymphocytes, granulocytes and macrophages in the milk itself raises the question of whether these "shed" milk cells might potentially serve a function with regard to protecting the suckling neonate from infection. The functionality of milk B-lymphocytes has remained particularly controversial. In this report, we describe the use of a novel technique of milk cell separation prior to cell culture and demonstrate the ability of colostral B-lymphocytes to elaborated immunoglobulin in response to antigenic stimulation using vaccine strain polio virus. (Pediatv Res 25:295-299, 1989Abbreviations BM, breast milk PBMC, peripheral blood mononuclear cells LeuOME, leucine 0-methyl ester PWM, pokeweed mitogen Although it is well established that human milk secretory IgA is produced locally in the lactating mammary gland, the ability of "shed" colostral B-lymphocytes to produce immunoglobulin in vitro has remained a topic of debate (I). Various groups of 'investigators have reported evidence that these cells will produce IgA under appropriate conditions (2-5), but others have failed to demonstrate functionality using similar methodologies (6-8). It might be hypothesized that these B-cells would not be fully functional on the basis of studies showing that colostral T-cells, natural killer cells, macrophages, and polymorphonuclear cells are generally hyporesponsive when studied in vitro. Reversing the argument, if the majority of colostral cell types exhibit some degree of functionality, then it is hypothetically probable that colostral B-cells retain activity. One difficulty encountered in the study of these cells is the abundance of IgA found within milk phagocytic cells, which easily obscures the relatively smaller amount of IgA that might be synthesized de novo. We have, therefore, used a novel method for the preparation of reasonably pure colostral lymphocytes and have tested the hypothesis of functionality by determining the ability of colostral B-cells to elaborate Ig in vitro in response to inactivated polio virus.

Immune components (IgA, IgM, IgG, immune cells) of colostrum of Bangladeshi mothers

“…This is because the mammary gland, considered as an immunological organ, 33 locally produces IgA 5–8,21 . The immunocompetent B lymphocytes in the mammary gland synthesize IgA 8,9,17,21 . The IgA class is relatively resistant to the proteolytic environment of gastrointestinal secretion that confers local immunity in the gastrointestinal tract of the infants 8,34 .…”

“…5 -8,21 The immunocompetent B lymphocytes in the mammary gland synthesize IgA. 8,9,17,21 The IgA class is relatively resistant to the proteolytic environment of gastrointestinal secretion that confers local immunity in the gastrointestinal tract of the infants. 8,34 IgA levels of individual colostrum can vary widely.…”

“…They are rich in immune components including immunoglobulins, predominantly IgA, and viable immune cells such as lymphocytes, macrophages, neutrophils, 2–12 and non‐immune bioactive compounds such as lactoferrin, lysozyme, and transferrin 11,13,14 . Even more, they contain certain antigen‐specific antibodies against both bacteria and viruses 15–20 …”

Immune Protection of Human Milk

“…Regarding the function of B lymphocytes, Slade and Schwartz [61] demonstrated their ability to elaborate IgA and IgM in response to antigenic stimulation.…”