It has recently been shown that an insertion (I)/deletion (D) polymorphism exists in the angiotensin-converting enzyme (ACE) gene, and that this polymorphism affects the serum ACE level. There are three genotypes: DD, DI, and II, with the ACE level highest in DD, intermediate in DI, and lowest in II. In the present investigation of the possible significance of the polymorphism for sarcoidosis, a total of 207 patients and 314 normal control subjects were examined. There were no significant differences in the I/D ratio and the genotype distribution between the two groups, and no significant variation in organ involvement (i.e., eye, skin, and heart) was noted among the three genotypes. To determine any prognostic influence of the polymorphism, we examined the disappearance ratio of abnormal shadow on chest radiography over 3 and 5 yr. No significant difference among the three genotypes was observed. New normal ranges of serum ACE level were determined for each genotype, and found to be 22% more sensitive overall than the conventional normal range and 39% more so for II type, suggesting an advantage for diagnosis and assessment of the disease activity of sarcoidosis.

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Interferon y (IFN-y) induces HLA-DR and -DQ molecules and causes an accumulation of transcripts in HL-60 cells. Experiments were, therefore, designed to investigate the intracellular signaling molecules regulating the appearance of HLA class II molecules. The expression of HLA class II (DR and DQ) molecules induced by IFN-y was blocked by a calmodulin antagonist, W7, but not by a protein kinase C inhibitor, H7. Furthermore, a direct activator of protein kinase C, phorbol 12-myristate 13-acetate, was unable to induce HLA class II (DR) molecule expression. These results suggest that IFN-y induces HLA class II molecules on HL-60 cells by way of a calcium-calmodulin pathway and not by way of a protein kinase C pathway. Calmodulin is activated by a transient rise in the cytosolic free calcium. In fact, IFN-y evoked a calcium influx into HL-60 cells, whereas depletion of Ca2+ from culture medium resulted in a failure of IFN-y to induce DR expression. Furthermore, the calcium ionophore A23187 by itself induced DR molecule expression. These results suggest that IFN-y stimulates calcium influx by a so-called receptor-mediated calcium channel and activates the calmodulin branch of the culcium messenger system, resulting in the induction of DR molecules on the surface of HL-60 cells.

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