HUMAN COLOSTRAL CELLS .1. SEPARATION AND CHARACTERIZATION

Google Scholar
  • 1 January 1979
    • journal article
    • research article
    • Vol. 38  (3) , 585-597
Abstract
Analyses of the cells present in human colostrum obtained from 54 healthy donors during the first 4 days of lactation revealed that there were 3.3 .times. 106 (range 1.1 .times. 105-1.2 .times. 107) cells/ml colostrum. Histochemical examinations showed that this population consisted of 30-47% macrophages, 40-60% polymorphonuclear leukocytes, 5.2-8.9% lymphocytes and 1.3-2.8% colostral corpuscles; epithelial cells were rare. The identity of various cell types was confirmed by Wright''s stain and by a series of histochemical techniques which disclosed the presence of nonspecific esterase, peroxidase and lipids. For further characterization, the different types of cells were separated by various methods, such as Ficoll-Hypaque density centrifugation, isokinetic centrifugation on a linear Ficoll gradient, adherence to glass or plastic and phagocytosis of carbonyl Fe. Immunohistochemical staining with FITC[fluorescein isothiocyanate]- and/or TRITC[tetramethylrhodamine isothiocyanate]-labeled reagents to Ig[immunoglobulin]A, IgM, IgG, .kappa.- and .lambda.-chains, secretory component, lactoferrin and .alpha.-lactalbumin were applied to unseparated and separated colostral cells. Polymorphonuclear leukocytes (staining for peroxidase), macrophages and colostral corpuscles (staining for nonspecific esterase) exhibited numerous intracellular vesicles that contained lipids and various combinations of milk proteins. Lymphoid cells did not stain with any of these reagents and plasma cells were not detected among the colostral cells. Individual phagocytic cells contained immunoglobulins of the IgA and IgM classes, .kappa. and .lambda. chains, secretory component, lactoferrin and .alpha.-lactalbumin. The coincidental appearance of these proteins in single, phagocytic cells but not in lymphoid cells indicates that the cells acquired these proteins by ingestion from the environment. Markers commonly used for the identification of B [bone marrow-derived] lymphocytes (surface Ig) and T [thymus-derived] lymphocytes (receptors for sheep red blood cells [SRBC]) were unreliable for the analysis of colostral cells (unless accompanied by subsequent morphological characterization) because strong fluorescence was observed on the surface of many non-lymphoid cells and because numerous macrophages and colostral corpuscles formed rosettes with SRBC. Lymphocytes, often found in association with colostral macrophages or corpuscles, were classified as T cells.