Optimum conditions for in vitro chicken IL-2 production and its in vivo role in Newcastle disease vaccinated chickens

Optimum conditions for in vitro chicken interleukin-2 (IL-2) production were studied. IL-2 containing culture supernatants were generated by mitogen stimulation of splenic mononuclear cells (SMC) and the samples were tested on 72 h Concanavalin A (ConA) blasts for their proliferative ability. 3H-thymidine incorporation was used as a measurement of proliferation. Higher stimulation indices and thus maximal IL-2 production were obtained with the following culture conditions: 5 × 106 cells ml−1 cultured for 24 h in the presence of 10 μg ml−1 ConA in serum free Iscoveʹs modified Dulbecco medium. The molecule responsible for IL-2 activity was found to have a molecular weight of 14 000 as estimated by size exclusion chromatography. SMC obtained from chickens inoculated with Newcastle disease virus were used to study the immunomodulatory role of IL-2. The lymphocyte transformation test was used as an in vitro correlate of cell mediated immunity in these chickens. The mitogen responses of cells obtained from virus inoculated and control chickens were similar on the basis of stimulation indices. Antigen specific lymphocyte proliferation was demonstrated using SMC obtained from virus inoculated chickens. Uptake of exogenous IL-2 by 72 h ConA blasts was of similar magnitude in both virus inoculated and control chickens indicating that uptake of IL-2 by T lymphocytes was normal in Newcastle disease virus inoculated chickens.