The proinflammatory and chondral activities of leukemia inhibitory factor in goat joints are partially a function of interleukin-1

We wished to determine if the effects of injected recombinant human leukemi a inhibitory factor (LIF) are a function of endogenous goat interleukin-1 ( IL-1) production and, conversely, if the effects of injected recombinant hu man IL-1 are a function of endogenous LIF production in goat radiocarpal jo ints (RCJ). In preliminary experiments, murine LIF binding protein (MuLBP) and recombinant HuIL-1RA were found to independently attenuate the cartilag e proteoglycan resorbing activity of goat synovial membrane-conditioned med ium (GSMCM), implying activity against goat LIF and goat IL-1, respectively . The present study shows that the proinflammatory and chondral actions of rHuLIF in goat RCJ are partially attenuated by rHuIL-1RA. This implies that a small but important component of the in vivo activity of rHuLIF is a res ult of IL-1 production in the synovial joint. With the exception of proteog lycan synthesis, the absence of significant effects by MuLBP on the actions of rHuIL-1 alpha in goat RCJ suggests that the proinflammatory and chondra l effects of IL-1 alpha in vivo are probably not mediated by LIF.