Acute anterior uveitis (AAU) is strongly associated with the genetic marker and cell membrane protein HLA-B27. Although also other genetic factors must play a pathogenetic role, the HLA-class I molecule B27 is up to now the only hold. The normal task of HLA class I molecules is to present endogenous, mostly viral, peptides to receptors on cytotoxic T cells. It is possible that HLA molecules at the cell surface serve as viral receptors. Human cytomegalovirus (HCMV) particles have been found to bindβ2m. This might promote infectivity by a binding to HLAα-chains on cell membranes. We studied this mechanism using mouse fibroblasts transfected for human HLA class I molecules. Susceptibility of these cells for HCMV was compared by measuring of HCMV immediate early antigen (IEA) expression. Earlier we observed that cells transfected with HLA-B27α- chains andβ2m were significantly more infected than cells expressing HLA-A2 +β2m or HLA-B7 or HLA-B27 withoutβ2m. However, studying another four, separately transfected, cell lines, all expressing HLA-B27 andβ2m, three of the five B27 cell lines showed low IEA levels. The degree of infectivity was independent of the degree of B27 expression. These results do not support the previous suggestion that HLA-B27 might act as an HCMV receptor.