I will try to summarize the evidence that immunosuppressive drugs may be useful in the therapy of connective tissue diseases. In order to simplify my task I will confine my discussion to two drugs-cyclophosphamide and azathioprine-because these are the two about which there is sufficient controlled information. For the same reason, I will also confine my discussion to their use in two diseases: rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).
T o begin with I would like to compare immunosuppressive agents with other drugs that are in common usage-first, penicillin. Penicillin kills the causative organism in pneumococcal pneumonia and certain other bacterial infections. Its value was obvious in uncontrolled trials despite occasional allergic reactions. The second drug is aspirin. This drug is of obvious benefit with rather little toxicity in most patients with RA. Although aspirin does not cure the disease as does penicillin, its modest toxicity is what enables it to be a very valuable drug. In contrast with these two drugs, immunosuppressive agents lack both of the beneficial properties. Although they probably are of benefit in RA and SLE, in neither disease are immunosuppressive drugs curative; therefore, they lack the major desirable characteristic of From the Arthritis and Rheumatism Branch, National Institute of Arthritis, Metabolism and Digestive Diseases,