HLA-DR4 and pulmonary dysfunction in rheumatoid arthritis.

Rheumatoid arthritis is associated with an increased frequency of the B cell alloantigen HLA-DR4, and preliminary work has suggested an association between HLA-DR4 and obstructive lung disease in subjects with rheumatoid arthritis. To prospectively evaluate the influence of HLA-DR4 on pulmonary involvement in patients with rheumatoid arthritis, pulmonary function was measured in four groups of subjects with rheumatoid arthritis in whom HLA-DR4 and smoking status was known: 16 DR4-positive smokers (six current and 10 exsmokers), 16 DR4-negative smokers (six current and 10 exsmokers), eight DR4-positive nonsmokers, and eight DR4-negative nonsmokers. Significant reductions in one-second forced expiratory volume and forced vital capacity were observed in DR4-positive subjects compared with DR4-negative subjects irrespective of cigarette smoking status. In addition, patients with keratoconjunctivitis sicca (secondary Sjögren's syndrome) demonstrated significant reductions in one-second forced expiratory volume, forced vital capacity, and ratio of one-second forced expiratory volume to forced vital capacity compared with those patients without evidence of secondary Sjögren's syndrome. It is concluded that the presence of the HLA-DR4 antigen and secondary Sjögren's syndrome are associated with abnormal pulmonary function in patients with rheumatoid arthritis.