Lymphocyte response to Klebsiella in ankylosing spondylitis

Serum antibodies to Klebsiella capsular polysaccharides in ankylosing spondylitis

OBJECTIVE

To measure antibodies to Klebsiella capsular polysaccharides in the sera of HLA-B27 positive patients with ankylosing spondylitis (AS), compared with HLA-B27 positive and HLA-B27 negative healthy control subjects.

METHODS

Antibodies were detected by means of an enzyme-linked immunosorbent assay specific for each of the 77 known Klebsiella serotypes.

RESULTS

Significantly elevated frequencies and titers of antibodies to capsular polysaccharides K26, K36, and K50 were detected in sera from AS patients, compared with controls.

CONCLUSION

These results suggest the predominance of Klebsiella serotypes K26, K36, and K50 in patients with AS.

Polyclonal B-cell activation by bacteria that induce nonsuppurative sequelae

The polyclonal B cell activation (PBA) process induced by Klebsiella pneumoniae K34 (klebs) and Yersinia enterocolitica 03 (yers) was investigated. Both heat-inactivated bacteria and their cell wall biostructures (klebsM, muriene, protein I etc.) stimulate human blood B cells to differentiate into immunoglobulin-secreting cells without prior proliferation and without T cells. Klebs-activated B cells secrete mainly IgM and to a lesser degree IgG (mainly IgG2). The PBA process was regulated by CD4+ cells and monocytes, but not by CD8+ cells. While interleukin 2 is able both to induce proliferation and to enhance differentiation in klebs-activated B cell cultures, the low-molecular-weight B cell growth factor (BCGF) did not lead to a significant amount of 3H-thymidine uptake. In addition, in klebs-activated B cell cultures various anti-polynucleotide autoantibodies and the 16/6 idiotype were detectable. Thus, bacteria that induce nonsuppurative sequelae (e.g. klebs, yers) can use several mechanisms to overcome tolerance in their host.