Ankylosing spondylitis and monoclonal gammopathies.

From 1960 to 1990, 557 patients with ankylosing spondylitis (428 men, 129 women) were diagnosed and indexed in the department of rheumatology. Monoclonal gammopathies were found in seven (five men, two women) patients (1.3%). With one exception, ankylosing spondylitis preceded monoclonal gammopathies by many years. The distribution of the isotypes of the mIg found in these seven patients was striking when compared either with previous reports of an association between ankylosing spondylitis and monoclonal gammopathies or with local data on the epidemiology of monoclonal gammopathies: five patients with IgG, four of them of the lambda (lambda) type, and two IgM, both of the kappa (kappa) type were found; no patients with mIgA were recorded. Two patients were HLA-B27 positive and had slight and transient monoclonal gammopathies, whereas three subjects were HLA-B27 negative and had important spikes, corresponding in two subjects to malignant diseases. This observation raises the question of whether the coexistence of HLA-B27 and ankylosing spondylitis might provide a protective action. Epidemiological studies are required to clarify such points.