Influence of age and parity on the distribution of cells expressing major histocompatibility complex class II, CD4, or CD8 molecules in the endometrium of mares during estrus.
OBJECTIVE
To evaluate effect of age and parity on distribution and number of cells expressing major histocompatibility complex (MHC) class II, CD4, or CD8 molecules in the endometrium of mares during estrus.


METHODS
32 gynecologically healthy mares, categorized as young (3 to 8 years; n = 17) or old (9 to 16 years; 15) and nulliparous (n = 6), nulliparous embryo donors (16), or parous (10).


METHODS
Endometrial specimens collected from the uterine body and horns during estrus were stained by use of the avidin-biotin-peroxidase method, using monoclonal antibodies against equine MHC class II, CD4, and CD8 molecules. Labeled cells in the stratum compactum within 5 randomly selected fields at 400x magnification (total area = 0.31 mm2) were counted, and numbers were compared among groups and between locations.


RESULTS
Age did not affect cell numbers within the 3 cell subsets examined. Numbers in each subset were higher in the uterine body than in the horns, although the difference was not significant for cells expressing MHC class II. Significantly more cells expressing MHC class II molecules were detected in the uterine body of nulliparous and parous mares than in embryo donors, whereas in the horns, these cells were significantly higher in number only in parous mares. Parity did not affect number of CD4+ or CD8+ cells.


CONCLUSIONS
The increased likelihood for endometritis to develop in mares as they age cannot be explained by a decrease in number of cells expressing MHC class II, CD4, or CD8 molecules within the endometrium. However, greater number of cells within these 3 subsets detected in the uterine body, compared with the horns, during estrus suggests a local readiness to act against microorganisms or semen introduced during mating or insemination.
Tunón
A M
AM
Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Centre for Reproductive Biology, Swedish University of Agricultural Sciences, Uppsala.
Rodríguez-Martínez
H
H
Nummijärvi
A
A
Magnusson
U
U
D000375:Aging; D000818:Animals; D015704:CD4 Antigens / Q000096:biosynthesis*; D016827:CD8 Antigens / Q000096:biosynthesis*; D002452:Cell Count; D004717:Endometrium / Q000378:metabolism*; D004971:Estrus; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis*; D006736:Horses / Q000276:immunology / Q000378:metabolism*; D010298:Parity; D020535:Video-Assisted Surgery
D015704:CD4 Antigens; D016827:CD8 Antigens; D000949:Histocompatibility Antigens Class II