Detection of different macrophage‐activating factor and interferon activities in supernatants of chicken lymphocyte cultures1

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Abstract
Chicken spleen lymphocytes were cultivated under various conditions in order to produce and characterise functionally avian lymphokines. Biological properties of lymphokine-containing culture supernatants were evaluated with regard to their antiviral activity and their effects on cultured bone marrow-derived chicken macrophages, including induction of cytostiatic activity, enhancement of phagocytic activity towards vital Candida albicans, and giant cell formation. Optimal doses of concanavaline A (ConA) for stimulation of lymphocytes varied between 2.5 and 40 .mu.g/ml, depending on the cell concentration and presence or absence of serum. Lymphokine production occurred even without exogenous mitogen stimulation when cells were cultured at sufficiently high concentration (1 to 2 .times. 107 cells/ml). Cytostasis-inducing capacity of lymphokine preparations against lymphoblastoid MDCC-RP1 cells was always combined with the presence of antiviral activity. Experimental results suggested that these two activities had to be attributed to at least two distinct lymphokines, i.e. macrophage-activating factor and interferon (IFN). ConA stimulation of lymphocytes from a single donor appeared to be the appropriate signal for production of IFN-.gamma.. Endogenous stimulation in mixed lymphocyte cultures more appropriately triggered production of IFN-.alpha. or IFN-.beta., although production of IFN-.gamma. was not completely suppressed. Phagocytic activity of macrophages could also be increased by a cytokine present in conditioned media from confluent cultures of chicken embryo fibroblasts, chicken kidney cells, or bone marrow-derived chicken macrophages. In lymphokine preparations, this mediator may even be a cofactor necessary for induction of multinucleated giant cell formation of cultured macrophages.