Lack of association with interleukin 1 receptor antagonist and interleukin-1beta gene polymorphisms in sarcoidosis patients.

Interleukin-1beta (IL-1beta) and its endogenous antagonist, the interleukin-1 receptor antagonist (IL-1ra), play important roles in immune responses. In sarcoidosis, IL-1beta is reported to be increased whereas IL-1ra is decreased. It has recently been shown that polymorphisms in the IL-1ra and IL-1beta genes may account for variation in the two proteins. These polymorphisms are also reported to be associated with several autoimmune diseases. Since this might be expected to affect sarcoidosis, an investigation of 108 sarcoidosis patients and 113 healthy control subjects was performed. The IL-1ra genotype was determined using the polymerase chain reaction (PCR), and the IL-1beta genotype by PCR restriction fragment length polymorphism. We found no significant differences in IL-ra and IL-1beta genotypes between sarcoidosis patients and healthy controls. Furthermore, there was no association between the IL-1beta genotype and the roentgenographic stage, disappearance of chest X-ray shadows or organ involvement. In conclusion, there is no bias in the IL-1ra and IL-1beta genotype in Japanese sarcoidosis patients.