Blood and milk cellular immune responses of mastitic non-periparturient cows inoculated with Staphylococcus aureus.
Lymphocyte function and phenotype of peripheral blood and mammary gland cells were evaluated in non-periparturient cows before and at 1, 4 to 8 and 9 to 14 d after inoculation with Staphylococcus aureus, as expressed by percentage of CD3+, CD2+, and CD45R+ cells, antigen density of these markers per lymphocyte, and mitogen-induced blastogenesis. Milk bacterial counts and somatic cell counts (SCC) were also assessed. Mitogen-induced blastogenic responses were strong in blood and weak in mammary gland cells in all observations and positively correlated with the percent of CD45R+ cells. Significantly greater percentages of milk CD3+ lymphocytes and increased CD3, CD2, and CD45R antigen density per cell were observed after challenge. The blood CD3 and CD2 antigen density per lymphocyte and the milk CD2+ lymphocyte percent were negatively correlated with SCC (P < or = 0.01). No mastitis (SCC < or = 500 000 cells/mL) was observed in cows showing blood lymphocyte CD2 and CD3 antigen density indices < or = 2.5 and 6, respectively. Forty-one percent of SCC values were predicted by the combined blood CD2 and milk CD3 antigen density (P < or = 0.01). These findings support the hypotheses that mitogen-induced lymphocyte blastogenesis is not a valid test to assess mammary gland immunocompetence and that CD2 expression may facilitate immune responses by decreasing the number of T cell receptors required to achieve full activation.
Rivas
A L
AL
Department of Population Medicine and Diagnostic Science, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA. alr4@cornell.edu
Tadevosyan
R
R
Quimby
F W
FW
Lein
D H
DH
D000818:Animals; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D005260:Female; D007111:Immunity, Cellular; D008213:Lymphocyte Activation; D018655:Lymphocyte Count / Q000662:veterinary; D016131:Lymphocyte Subsets / Q000276:immunology; D008414:Mastitis, Bovine / Q000175:diagnosis / Q000276:immunology* / Q000382:microbiology; D008892:Milk / Q000166:cytology* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000276:immunology*; D013997:Time Factors