We investigated the incidence of herpes zoster (HZ) and the immunological state toHZ in patients with rheumatoid arthritis (RA) and mixed connective tissue disease (MCTD) in comparison with systemic lupus erythematosus (SLE). HZ occurred in 6 (25%) out of 24 patients with RA and 4 (22%) out of 18 patients with MCTD. One patient had had HZ before the diagnosis of RA. On the other hand, all 4 patients with MCTD had had HZ before the diagnosis of MCTD.
The patients with RA and MCTD showed normal or higher antibody titers to varicella zoster virus (VZV) than normal subjects as assayed by both complement fixation technique and neutralization test. However, the antibody levels were not very high compared to those in patients with SLE. On the other hand, only 7 (50%) of 14 patients with RA and 4 (40%) of 10 patients with MCTD showed positive skin reactions to VZV antigen, whereas all 15 normal subjects had positive reactions. Thus, cellular immunity to VZV was thought to be impaired in these diseases. In the patients who were receiving less than 10 mg/day of prednisolone, 7 (64%) of 11 had positive skin reactions in RA patients and 3 (60%) out of 5 patients with MCTD, whereas none (0%) out of 3 patients with RA and 1 (20%) out of 5 patients with MCTD who were receiving 10 mg/day or more prednisolone showed positive skin reactions.
These results suggest that the high incidence of HZ in patients with RA and MCTD is probably due to an impaired cellular immunity as in the case of SLE.