Changes in protein synthesis due to an inflammatory challenge.

Rates of protein synthesis in various chick tissues were examined 16 hr after an inflammatory challenge. Protein synthetic rates were calculated from the rate at which [14C]leucine was incorporated into protein and the specific activity of [14C]leucine in the precursor pool. An injection of either Escherichia coli or sheep red blood cells (SRBC) decreased the rate of protein synthesis in the gastrocnemius muscle, and increased the rate in liver, bursa, spleen, and thymus. E. coli, but not SRBC, decreased protein synthesis in the pectoralis muscle. E. coli significantly decreased the aggregation of pectoralis muscle polysomes and increased the aggregation of polysomes in the thymus, bursa, and spleen. E. coli increased the aggregation of free, but not bound, polysomes in liver, suggesting an increase in synthesis of export proteins. SRBC significantly increased polysomal aggregation in bursa and spleen only. A crude preparation of leukocyte endogenous mediator, isolated from peritoneal macrophages, decreased muscle-polysomal aggregation. These studies indicate that tissue-specific changes in protein synthesis occur after a noninfectious inflammatory challenge. These changes may be part of a homeostatic mechanism which supports the immune response.