Immune function in ankylosing spondylitis: apparent relationship between streptococcal responses and HLA B27

Immune function has been evaluated in 54 patients with ankylosing spondylitis (AS) and 26 controls. Cell-mediated immunity was assessed by skin testing with ubiquitous antigens, and humoral immunity by antibody responses to tetanus toxoid and Salmonella typhi vaccinations, and resting titres of anti-Streptolysin O, anti-E Coli, and isohemagglutinins. The AS patients had reduced delayed hypersensitivity responses to Candida, augmented responses to Streptococcal antigen and relatively low ASO titres. There was no generalized depression of humoral immunity, as indicated by the normal tetanus and Salmonella O responses and hyper-response to Salmonella H antigen. The E. Coli and isohemagglutinin titres were normal. These results indicate that patients with AS present a complex immunological profile, including exaggerated responses to some antigens and impaired responses to others. In view of the very high incidence of HLA-B27 in AS, it is possible that these findings are related to the effects of HLA associated immune response genes.