Suppression of adjuvant arthritis in rats by transfer of cultured spleen cells.

We studied the in vivo effect of transfer of nonspecific suppressor spleen cells into syngeneic Lewis rats. The rats were immunized with Freund's adjuvant on day 0, and then given 5 X 10(7) cells on days--7, 0 and 7. These cells had been incubated for 3 days, with or without mitogenic stimulation. Transfer of the cultured cells markedly diminished the severity of adjuvant arthritis (AA). On the contrary, transfer of concanavalin A (Con A)-stimulated cells led to no suppressive activity. These results differed from findings in a prior in vitro experiment, in which the suppressive influence of previously cultured cells on T and B lymphocytes proliferation rates was examined and significant suppressive activity was detected in Con A-stimulated cells but not in cultured cells. Suppressor activity by transfer of solely cultured cells was identified in T cell fractions. Transfer of 5 X 10(7) spleen cells proved to be the optimal dose for suppressing AA, and transfer of less than 2 X 10(7) cells had no significant effect. The number and time of transfer were also important factors in the suppression. Each group of transfer on days--7, 0 and 7, days--7 and 0, and days 0 and 7 led to a similar reduction in the severity of AA, and was less prominent in the group injected on days 7 and 14. A single injection on days--7, 0, or 7 revealed minimal or no effects. These observations indicate that the transfer of in vitro cultured spleen cells nonspecifically modified the course of rat AA in vivo, thereby differing from the results of the suppressor activity seen in vitro. The transfer of cultured cells, as a potential tool for the treatment of clinical diseases warrants further attention.