The distribution of prostaglandins in afferent and efferent lymph from inflammatory sites

Arachidonic acid labeled with (14)C was injected directly into lymph nodes that had been stimulated at various times with Escherichia coli. The efferent lymph was collected, and labeled catabolites were extracted and analyzed chromatographically. The pimary conversion product recovered was Prostaglandin E(2) (PGE(2)), with the lesser products thromboxane, prostacyclin and prostaglandin F(2alpha) (PGF(2alpha)) also detected. When the efferent lymph was analyzed by radioimmunoassay after subcutaneous injectino of E coli into the hock, PGE and PGF levels rapidly increased, reached the highest levels in the first 10 hours, and then returned to normal by 24 hours. When the afferent lymph plasma draining inflammatory sites was compared directly with efferent lymph, PGF levels were similar, but the PGE level was always several times higher in the afferent lymph. To examine the catabolism of PG, either (3,)H-PGF(2alpha) of (3)H-PGE(2) was injected into the node, and the efferent lymph plasma was analyzed. No conversion of PGF(2alpha) to other products was found. In contrast, catabolic products of PGE(2) were detected. With the use of equilibrium dialysis techniques, the binding of PGE(2) and PGF(2alpha) to proteins in lymph and to bovine serum albumin (BSA), human serum albumin (HSA), and BSA stripped of its fatty acids was established. The binding to lymph proteins correlated with the albumin concentrations in the lymph. This albumin binging probably facilitated the retention and transport of PG in the lymph. PG appears in the lymph at a time corresponding to the uptake and processing of antigen by the node and near the time when lymphokines are detected in lymph and could modulate several steps in the immune response. The PGE detectable in the lymph draining an inflammatory site may play a role in the modulation of blood flow.