[Immunohistochemical study on human colostral cells]

Colostrum contains a large number of cells and humoral defence factors that play an important role in the protection of neonates. While colostral cells have been characterized by immunohistochemical criteria, the function of these cells has been poorly understood. In this study, localization of immunoglobulins and other components in human colostral cells was examined by an immunofluorescence technique. The results obtained were as follows: Colostral cells reactive with polyvalent anti-human immunoglobulins were neutrophils and macrophages with a granular staining pattern. The predominant immunoglobulin in colostral cells was IgA, followed by IgM. A small amount of IgG was also found in these cells. The distribution of SC was similar to that of IgA and J-chain, suggesting the presence of secretory IgA in colostral cells. Coincidence of kappa chain and lambda chain in the same granules of neutrophils and macrophages suggests that these immunoglobulins were phagocytosed by neutrophils and macrophages. This conclusion was supported the results of the experiment which showed that incubation of peripheral blood neutrophils and monocytes with cell free colostrum resulted in the appearance of immunoglobulins in granules.