Clearnace of Fe59-labelled erythrocytes from normal and inflamed rabbit knee joints. I. Relationship to the anaemia of rheumatoid arthritis.

The anaemia of rheumatoid arthritis has features suggestive of iron deficiency even in the absence of occult blood loss (Jeffrey, 1965). There is some evidence that this may be due to reduced availability of iron from storage sites in the reticulo-endothelial system (Weinstein, 1959; Owen and Lawson, 1966). Extensive deposits of iron are frequently found in the synovial membrane in this disease and these have recently been considered as a further important storage site for iron (Muirden and Senator, 1968; Mowat and Hothersall, 1968). Sequestration of iron in the synovium could contribute to the hypoferraemia and anaemia of this condition. To test this hypothesis a study was made of the clearance of Fe59 labelled to red blood cells from inflamed and normal knee joints of rabbits. The radiation was measured by surface counting and by liquid scintillation of ashed segments of tissue. The eventual distribution of iron in the joint was measured histochemically and by autoradiography and these results will be described in a subsequent paper.