HLA-B27 does not affect invasion of arthritogenic bacteria into human cells

OBJECTIVE: To investigate the effect of HLA-B27 expression on entry of Salmonella typhimurium and Yersinia enterocolitica into human cells. METHODS: We performed standard bacterial invasion assays with S. typhimurium and Y enterocolitica to analyze isogenic pairs of HeLa (epithelial), U937 (promonocyte), C1R (B lymphocyte), and Jurkat (T lymphocyte) human cell lines and their respective HLA-B27 transfectants. Invasion of peripheral blood derived T lymphocytes, monocytes, and B lymphocytes/dendritic cell fraction (corresponding to peripheral blood cells depleted of monocytes and T lymphocytes) from patients with ankylosing spondylitis and healthy donors was also analyzed. The percentage of internalized bacteria was quantified, and the differences between HLA-B27 positive and negative samples were compared. RESULTS: The percentages of intracellular S. typhimurium and Y enterocolitica in HeLa, U937, and C1R with or without B27 were not statistically different (independent t test). We also found that the percentage of internalized bacteria did not differ significantly between HLA-B27 positive and negative samples in the different populations of peripheral blood derived cells. CONCLUSION: The presence of HLA-B27 on the surface of human cells does not alter the degree of bacterial invasion into either cultured human cell lines or peripheral blood derived human cells, and the influence of HLA-B27 expression on bacterial invasion should not be implicated in the pathogenesis of reactive arthritis related to Salmonella and Yersinia.