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Serum MIF activity was studied in ten patients with sarcoidosis, fourteen with granuloma annulare, four with necrobiosis lipoidica, and nine with various dermatological diseases. Positive MIF activity was found in the sera of nine of the ten patients with sarcoidosis and eleven of the fourteen patients with granuloma annulare. The delayed hypersensitivity tests were negative in all nine of the patients with sarcoidosis who had serum MIF activity and were positive in only three patients with cutaneous sarcoid lesions. One of four patients with necrobiosis lipoidica demonstrated minimal serum MIF activity. Data on serum lymphokine activity in sarcoidosis and granuloma annulare suggest that these two diseases are related to delayed hypersensitivity mechanisms.

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Heparin causes enhanced nitroblue tetrazolium (NBT) reduction by polymorphonuclear leukocytes (PMN's). To determine the mechanism of this stimulation, samples of 1 to 3 x 10(7) PMN's were incubated with various concentrations of heparin, chondroitin sulfate A (CSA), and chondroitin sulfate B (CSB), with and without NBT. The effect of the polyanions (PA) on PMN hexose monophosphate shunt (HMPS) activity was determined by the production of 14CO2 from glucose-1-14C by the leukocytes. NBT reduction was evaluated histochemically and spectrophotometrically at 515 mmu. Samples of PMN's in heparin and heparin-NBT mixtures were examined by electron microscopy after various incubation periods. Increased NBT reductions by PMN's was found when leukocytes were incubated with heparin, CSA, and CSB, but these compounds had no effect on the HMPS activity of PMN's unless NBT was added. Electron microscopy of samples that contained heparin-NBT revealed an insoluble complex that was phagocytosed by the leukocytes. The stimulation of PMN oxidative metabolism and NBT reduction that follows incubation with PA-NBT appears to be directly related to ingestion of this particulate complex by the leukocytes.