Minimal alterations in the HLA-B27-bound peptide repertoire induced upon infection of lymphoid cells with Salmonella typhimurium.

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-B2705. HLA-B27-bound peptide pools were isolated from noninfected and infected B2705+ 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 B2705 did not influence S typhimurium invasion, since this was equally efficient in nontransfected or B27-transfected cells. The chromatographic profiles of B2705-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.

CONCLUSION

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.