The enhancement of avian NK cell cytotoxicity by thymulin is not mediated by the regulation of IFN-gamma production.
Preincubation with either thymulin or IFN-gamma can enhance NK activity. In addition, overnight in vitro pre-treatment with thymulin and IFN-gamma increases NK activity further than either treatment alone. It has been hypothesized that thymulin increases the responsiveness of immune cells to IFN-gamma by either increasing the expression of IFN-gammaR or by increasing the production and/or secretion of IFN-gamma. The effects of thymulin on IFN-gamma production and secretion were examined in this study. While an overnight incubation with the polyclonal activator Con A increased the number of cells positive for intracellular IFN-gamma, a similar incubation with thymulin produced no change in the percentages of cells labeling positive for intracellular IFN-gamma when compared to the media control cells. In addition, IFN-gamma was not secreted by splenocytes following an overnight incubation with thymulin, but increased secretion was induced by Con A stimulation. Taken together, these results suggest that thymulin does not increase IFN-gamma production or induce IFN-gamma secretion by avian splenocytes.
Merlino
P G
PG
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, C5-VMC, Ithaca, NY 14853, USA.
Marsh
J A
JA
D000818:Animals; D002645:Chickens; D003602:Cytotoxicity, Immunologic; D007371:Interferon-gamma / Q000096:biosynthesis*; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D008297:Male; D013935:Thymic Factor, Circulating / Q000494:pharmacology*
D007371:Interferon-gamma; D013935:Thymic Factor, Circulating