Studies on the infectious etiology of rheumatoid arthritis

Aetiology of rheumatoid arthritis: an attempt to transmit an infective agent from patients with rheumatoid arthritis to baboons

Thirty baboons were injected intravenously and intra-articularly with material from the joints of 19 patients with active rheumatoid arthritis or with control material. Fifteen of the 30 animals received synovial fluid cells or synovial membrane cells from 3 patients with seronegative arthritis. Ten animals received pooled cells from a total of 16 cases of seropositive arthritis. Five animals were given nonrheumatoid cells. No signs of arthritis were recognised in the 27 surviving animals during 3 years of observation. No significant biochemical, haematological, or serological changes occurred during this period, and no gross or microscopic evidence of synovial or systemic disease was found post mortem.

Cytotoxic activity of rheumatoid and normal lymphocytes against allogeneic and autologous synovial cells in vitro

The possibility that lymphocytes from patients with rheumatoid arthritis (RA) might be sensitized to RA synovial cell antigens was investigated with a 51Cr release cytotoxicity assay. Peripheral blood lymphocytes from rheumatoid and normal donors were tested for cytotoxic activity against their own synovial cells and against allogeneic rheumatoid and nonrhemuatoid synovial cells. In the allogeneic studies, the degree of cytotoxicity was significantly influenced by the age in culture (passage number) of the synovial target cells (P less than 0.001). When the passage number of the target cells was considered in the analysis, rheumatoid lymphocytes were found to have greater cytotoxic activity than normal lymphocytes against young cultures (low passage number) of both RA and non-RA synovial cells (P = 0.0042). Differences in susceptibility to lysis between RA and non-RA synovial cells were more susceptible to both RA and normal lymphocyte-induced lysis than were non-RA synovial cells (P = 0.0048). No evidence of cytotoxicity was detected when lymphocytes from nine RA patients and two osteoarthritis patients were reacted against their own synovial cells. Although the data demonstrated an increased cytotoxic activity of peripheral blood lymphocytes from some RA patients against allogeneic synovial cells, the fact that this reactivity was seen against both non-RA and RA synovial cells and was not demonstrated against autologous synovial cells argues against the presence of an immunospecific response of RA lymphocytes to RA synovial cell antigens.

Arthritis of mice induced by Mycoplasma pulmonis: humoral antibody and lymphocyte responses of CBA mice

Peak arthritis occurred 14 days after intravenous injection of Mycoplasma pulmonis and persisted in some mice at low levels for 84 days. A marked lymphocytosis occurred during the first week of infection with only a slight increase in polymorphonuclear leukocytes. Complement-fixing antibodies appeared in low titer 3 days after infection and moderate levels persisted for 84 days. The metabolic-inhibiting and mycoplasmacidal antibody responses were absent or minimal. M. pulmonis appeared to be mitogenic for mouse lymphocytes as evidenced by (i) increased uptake of [3H]thymidine for normal lymphocytes exposed to various concentrations of nonviable M. pulmonis antigen, and (ii) a 13-fold increase in [3H]thymidine uptake in lymphocytes taken from mice 3 days after infection with M. pulmonis in the absence of added antigen. Lymphocytes taken from infected mice transformed significantly more at all time periods than control lymphocytes when exposed to M. pulmonis antigen. This response was maximal at 3 days and minimal at 21 to 35 days after infection. Lymphocytes sensitized to M. pulmonis did not transform when exposed to M. arthritidis antigen or vice versa. M. pulmonis infection had no effect upon the mitogenic responses of lymphocytes to phytohemagglutinin or lipopolysaccharide. There was no statistically significant correlation between persistence of arthritis and degree of humor antibody or lymphocyte responses. However, persisting arthritis was associated with a higher incidence of mycoplasma isolations.

Studies on the infectious etiology of human rheumatoid arthritis. II. Search for humoral and cell-bound antibodies against mycoplasmal antigens

A total of 29 rheumatoid patients and 19 nonrheumatoid patients were tested for evidence of present or past infection by M pneumoniae, M hominis, M fermentans, M arthritidis, M pulmonis, and M hyorhinis. The techniques of lymphocye transformation, metabolic-inhibiting antibody test, and mycoplasmcidal antibody test indicated no significant difference in the response of rheumatoid as opposed to nonrheumatoid patients.