Immunodeficiencies associated with sulphasalazine therapy in inflammatory arthritis

Abnormalities in serum immunoglobulin levels (Igs) are documented in a series of 350 patients with rheumatoid arthritis (RA) and other inflammatory joint diseases treated with sulphasalazine (SASP) for up to 10 years. Low Ig levels occurred in just over 10% of patients after therapy. Three per cent developed selective IgA deficiency between 8 and 20 weeks after starting SASP. Low IgG levels occurred in 2% at 4-52 weeks and low IgM levels in 5% after 3-7 months. One per cent developed panhypogammaglobulinaemia (hypo gamma) 3-7 months after commencing therapy. Most immunodeficiencies were not accompanied by other toxic reactions and SASP was continued in all but one patient with a rash and thrombocytopenia. A good clinical response was observed in most patients particularly those with selective IgA deficiency and hypo gamma. Two patients with hypo gamma developed chest infections which responded to antibiotics. A low level of individual Igs is not usually an indication to stop SASP unless accompanied by other reactions. Panhypo gamma is potentially serious and should be monitored carefully and replacement therapy should be considered in these patients if infections occur.