Identification by cell electrophoresis of a subpopulation of polymorphonuclear cells which is increased in patients with rheumatoid arthritis and certain other rheumatological disorders.

Two and occasionally three electrophoretic subpopulations of polymorphonuclear cells (PMNs) were identified in the blood of normal healthy subjects and patients with rheumatoid arthritis (RA). Most of the PMNs from both groups of subjects were found in the population with the highest surface charge; the remainder being in the other distributions, which were collectively termed the slow cell population. There was a significant increase in the percentage of rheumatoid PMNs (mean 42%) ascribed to the slow population when compared with PMNs from normal subjects (mean 17%). A similar increase in the slow cell population was also seen in patients with Felty's syndrome (mean 38%) and scleroderma (mean 51%), but not in patients with Behçet's syndrome (mean 18%). Synovial fluid aspirated from the knee joints of patients with RA contained PMNs with the lowest surface charge. With nylon fibre as an adherence substrate cells of a low surface charge were found to be more adherent than those of a high surface charge. An alteration in the electrophoretic distribution of PMNs may represent changes that are related to the expression of functionally related membrane ionogenic groups.