Background: B7 proteins (CD80, CD86) are costimulatory molecules expressed on antigen-presenting cells and are essential factors for T cell activation. Objectives: The aim of this study is to investigate the relationship of B7 gene polymorphisms either to disease susceptibility or to cell profile of bronchoalveolar lavage (BAL) fluid in Japanese sarcoidosis patients. Methods: Gene polymorphisms located in CD80 promoter, CD80 exon 3 and exon 8 of CD86 were examined in 146 Japanese sarcoidosis patients and 157 healthy controls using single-strand conformation polymorphism and direct sequencing. The distribution of genotypes was compared between the two groups. BAL fluid cell profiles were compared for the various genotypes of the different polymorphisms for the 62 patients who underwent BAL. Results: There were no significant differences in the distribution of genotypes or allele frequencies for all polymorphisms between sarcoidosis and controls. There were no significant differences in BAL fluid cell profiles among the different genotype groups of the various polymorphisms studied. Conclusions: There was no relationship between the B7 gene polymorphisms studied and disease susceptibility or BAL fluid cell profiles in Japanese sarcoidosis patients. Copyright (C) 2005 S. Karger AG, Basel.