Preferential production and secretion of immunoglobulins by the equine endometrium--a mucosal immune system

Immunoglobulin concentrations were compared in serum and in saline uterine washings from 10 normal mares and 7 subfertile mares with chronic endometrial pathology. Samples were collected in dioestrus and in oestrus. For each immunoglobulin class (IgA, IgG, IgG(T), IgM) the results were expressed as a percentage of total immunoglobulin present in uterine washings or serum. Comparison was also made between changes in immunoglobulin concentrations between dioestrous and oestrous uterine samples, and uterine immunoglobulin concentrations between groups of mares. There was significantly more IgA in the uterus than in serum and a significant change in uterine total immunoglobulin and IgG concentrations between dioestrus and oestrus in normal mares; both were higher in dioestrus than in oestrus. There were no significant changes in IgA, IgG(T), IgM in normal mares between dioestrus and oestrus, nor in total immunoglobulin, IgA, IgG, IgG(T) and IgM in subfertile mares. Subfertile mares had significantly higher total immunoglobulin, IgA and IgG concentrations in uterine fluid than did normal mares. Indirect immunofluorescent staining for equine IgA, IgG, IgG(T) and IgM was carried out on endometrial biopsy specimens. Epithelial IgA in normal mares and epithelial, glandular secretion and plasma cell IgA in subfertile mares were demonstrated. Specific fluorescence for other immunoglobulin classes was not noted.