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Exercise is commonly used in the management of patients with rheumatoid arthritis

Background-Increased numbers of apoptotic neutrophils, and impaired monocyte/macrophage clearance of apoptotic cells, have been demonstrated in systemic lupus erythematosus (SLE). CD44 is implicated in the clearance of apoptotic neutrophils. Objective-To determine the expression of CD44 on peripheral blood monocytes and neutrophils in SLE, and examine the relations with disease activity and numbers of circulating apoptotic neutrophils. Methods-Peripheral blood was sampled from 31 patients with SLE, 19 healthy normal subjects, and 19 patients with rheumatoid arthritis (RA). Monocyte and neutrophil density of surface CD44 expression was determined by immunofluorescence labelling and flow cytometry, and results expressed as mean channel fluorescence (MCF) values. Neutrophil apoptosis was measured by morphology in 15 patients with SLE, nine with RA, and six normal subjects. Results-Monocyte CD44 expression was significantly lower in SLE (median MCF 4.71) than in healthy normal subjects (median MCF 5.61) and controls with RA (median MCF 5.39). Neutrophil CD44 expression was also significantly lower in SLE (median MCF 1.95) than in healthy normal subjects (median MCF 2.37) and controls with RA (median MCF 2.60). Monocyte, but not neutrophil, CD44 expression correlated negatively with the percentage of apoptotic neutrophils. There was no significant correlation of monocyte or neutrophil CD44 expression in SLE with disease activity or damage. Conclusions-Monocyte and neutrophil CD44 expression is reduced in SLE, and this may contribute to the impaired recognition and clearance of apoptotic neutrophils by monocyte derived macrophages. (Ann Rheum Dis 2001;60:950-955) Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease in which tissue damage can best be explained by the production of pathogenic autoantibodies and their participation in immune complex formation. The description of nuclear autoantigen expression (including Ro, La, and dsDNA) on cytoplasmic blebs of apoptotic cells provides an attractive explanation for the unique clustering of autoantibodies in SLE.

Most human peripheral blood monocytes strongly express surface CD14, but not CD16 (CD14+ +/CD 16-). A smaller group of monocytes express lower levels of CD14 and also express CD16 (CD14+/CD16+). This subgroup has different functional characteristics and is expanded in a number of disease states. We aimed to determine the percentage of circulating CD14+ /CD16+ monocytes in rheumatoid arthritis and systemic lupus erythematosus (SLE) and relate this to disease measures. Peripheral blood was sampled from 31 SLE patients, 19 rheumatoid arthritis patients, and 19 healthy controls. The percentage of CD14+/CD16+ monocytes was determined by immunofluorescence labelling and dual colour flow cytometry. The percentage of CD14+/CD16+ monocytes was significantly lower in rheumatoid arthritis (median 4.90%) than in normal subjects (median 7.30%, P = 0.014), and in rheumatoid arthritis than in SLE patients (median 9.40%, P = 0.009). The percentage of CD14+/CD16+ monocytes in SLE was not significantly different from that in healthy subjects. This lower percentage of CD14+/CD16+ monocytes in rheumatoid arthritis may be important in the pathogenesis of this disease.

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