Objective: To characterize putative changes in the HLA-B27-bound peptide repertoire following infection of lymphoid cells with Salmonella typhimurium, a bacterium known to trigger reactive arthritis in HLA-B27-positive individuals.

Methods: A protocol was developed for efficient large-scale infection of lymphoblastoid cell transfectants expressing HLA-B*2705. HLA-B27-bound peptide pools were isolated from noninfected and infected B*2705+ cells and comparatively analyzed by high-performance liquid chromatography. Peptide-containing chromatographic fractions from noninfected and infected cells were systematically compared by mass spectrometry (MS) to look for putative differences at the level of individual peptides.

Results: The presence of B*2705 did not influence S typhimurium invasion, since this was equally efficient in nontransfected or B27-transfected cells. The chromatographic profiles of B*2705-bound peptides from noninfected and infected cells were virtually identical. A total of 808 molecular species were compared by MS. Of these, 807 were present in both infected and noninfected cells. Only one molecular species from infected cells lacked a detectable counterpart in noninfected cells.

Conclusions: Intracellular infection of lymphoid cells by S typhimurium induces minimal alterations in the HLA-B27-bound peptide repertoire. Minor changes detectable by cytotoxic T lymphocytes, but not easily amenable to direct biochemical analysis, are not ruled out.