Rheumatoid arthritis and chronic lymphatic leukaemia.

There is evidence for an increased incidence of lymphoproliferative disorders in patients with rheumatoid arthritis (RA). We present the clinical features of 4 patients with RA and chronic lymphatic leukaemia (CLL) which, occurring in a population of 1505 RA patients, represents a significantly increased prevalence of CLL (p less than 0.05) compared to the general population. These patients had significantly lower natural killer cell activity than matched rheumatoid controls (p less than 0.05) or normal controls (p less than 0.01) and we discuss this as a possible mechanism of association.