[An HLA-B27 negative case of ankylosing spondylitis with acute iridocyclitis].

The author experienced a 34-year-old male case of acute iridocyclitis with fibrinous exudates accompanied by ankylosing spondylitis with negative HLA-B27. Who was diagnosed definite ankylosing spondylitis by the New York criteria. The cause of ankylosing spondylitis was postulated to be a cross reaction between HLA-B27 and a certain Gram-negative bacillus. However, our case with negative HLA-B27 suggested the causes could comprise multiple factors in addition to HLA-B27. Since the clinical picture of iridocyclitis observed in our case showed no difference with those of HLA-B27 positive cases, iridocyclitis associated with ankylosing spondylitis is considered to be the same entity regardless of HLA-B27 being present or not.