T and NK cell subset changes with microbial extracts and human HSP60-derived peptides in Behçet's disease

Microorganisms such as streptococcus and autoantigens such as 60 kD heat-shock protein (HSP60) are implicated in the etiopathogenesis of Behçet's disease (BD).

Peripheral blood mononuclear cells from patients with BD (n = 16) and healthy controls (HC) (n = 11) were cultured for 5 days with extracts of S. sanguis-KTH-1 (SS), E. coli (EC) and a mixed peptide combination from human HSP60 (aa 136-50, 179-97, 224-58 and 336-51) reported to be associated with BD. T and NK cell subset changes were determined by flow cytometry.

In unstimulated 5-day cultures gammadelta+ (both CD4+gammadelta+ and CD8+gammadelta+), CD8+alphabeta+, CD4+CD56+ and CD8+CD11b+ cells were increased in BD compared to HC. In antigen-stimulated cultures of BD patients CD3+ and alphabeta+ T cells responded to HSP60 peptides whereas EC stimulated only CD16/ CD56+ NK cells. In the control group, similar to BD, alphabeta+ and CD4+ T cells responded to HSP60 peptides, however SS and EC mainly activated cytotoxic T cell subsets (CD8+CD11b and CD4+CD56+ T cells).

Significant increases in unstimulated T cell subsets suggest the presence of an in vivo T cell activation in BD. In both patients and controls similar patterns of responses were observed against different microorganisms, however the role of human HSP60 peptides as immunodominant, crossreactive antigens could not be demonstrated.