Cytologic responses of Staphylococcus aureus-infected mammary glands of heifers to interferon gamma and interleukin-2 treatment.
Cytologic and bacteriologic responses, and changes in cytokine activity were evaluated in secretions of Staphylococcus aureus-infected mammary glands after treatment of heifers with recombinant bovine interferon gamma (rbIFN gamma) or interleukin 2 (rbIL-2). Two groups of 4 heifers each, experimentally infected with 10(7) colony-forming units (CFU) of S aureus, were injected in 2 quarters via the teat canal, with 10(5) U of rbIFN gamma (trial 1) or 7.5 x 10(5) U of rbIL-2 (trial 2) 2 weeks after experimentally induced infection; control quarters received phosphate-buffered saline solution. Mammary secretion samples were taken on days 0, 1, 2, 3, 4, 7, and 14 after cytokine infusion. Secretions were diluted 1:10 and used to perform somatic cell counts (SCC), differential cell counts, and CFU enumerations, and to determine the number of leukocytes expressing major histocompatibility complex class-II (MHC II) antigens. In addition, mammary secretion samples taken on days 0, 1, and 2 were processed to obtain skimmed milk for evaluation of rbIFN gamma- and rbIL-2-like activities. Treatment with rbIFN gamma did not influence SCC, or differential or bacteria counts, or the number of leukocytes expressing MHC II antigens. However, rbIL-2 stimulated leukocytosis, which may have reduced bacteria counts early in the trial; treatment with this cytokine also increased the neutrophil, macrophage, lymphocyte, and eosinophil counts in secretions. Similarly, numbers of MHC II-positive leukocytes were greater in rbIL-2-treated quarters vs controls. Compared with day 0, IFN-gamma-like activity was increased on only day 1 in both trials.(ABSTRACT TRUNCATED AT 250 WORDS)
Quiroga
G H
GH
Mastitis Research Laboratory, Louisiana State University Agricultural Center, Homer 71040.
Sordillo
L M
LM
Adkinson
R W
RW
Nickerson
S C
SC
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007371:Interferon-gamma / Q000627:therapeutic use*; D007376:Interleukin-2 / Q000627:therapeutic use*; D007962:Leukocytes / Q000276:immunology / Q000473:pathology; D008321:Mammary Glands, Animal / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008414:Mastitis, Bovine / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D011994:Recombinant Proteins; D013203:Staphylococcal Infections / Q000276:immunology / Q000628:therapy / Q000662:veterinary*
D000949:Histocompatibility Antigens Class II; D007376:Interleukin-2; D011994:Recombinant Proteins; D007371:Interferon-gamma