Relationship of HLA-DR4 to defective cellular immunity in rheumatoid arthritis using PPD, and mycoplasma and lectin mitogens.

The disordered cellular immunity of rheumatoid arthritis (RA) was studied in vitro by assessing the stimulatory effect of tuberculin PPD, a mycoplasma product with major histocompatility complex restricted properties in mice (MAS) and concanavalin A (Con A) on RA and control cells of known tissue type. PPD provided the best discrimination between RA and controls (RA responses 34% of latter). The only significant association with HLA-DR type was that patients with RA who exhibited poor responsiveness to MAS had a significantly increased frequency of HLA-DR4.