Transfer of spleen cells expanded by T cell growth factor suppresses arthritis induced in rats.

The effects of transfer of T cell growth factor (TCGF)-expanded spleen cells after concanavalin A (Con A) stimulation into syngeneic Lewis rats were studied. The recipient rats were immunized with complete Freund's adjuvant for induction of adjuvant arthritis (AA) or chick type II collagen in incomplete Freund's adjuvant for induction of collagen-induced arthritis (CIA) on day 0. Each of 5 X 10(7) cultured cells without mitogenic stimulation, 2 X 10(7) Con A-stimulated cells, or 1 X 10(7) TCGF-expanded cells cultured for 8 days (4 days X 2 culture cycles) after Con A stimulation was given on days 0 and 7. Both transfers of the cultured cells without stimulation and TCGF-expanded cells markedly diminished the severity of AA and CIA. On the contrary, transfer of Con A-stimulated cells led to no suppressive activity. In addition, transfer to TCGF-expanded cells significantly lowered the titre of anti-type II collagen antibody compared to that of control rats. The transfer of 1 X 10(7) TCGF-expanded cells was optimal for suppressing AA, in terms of cell number. This observation suggests that these cells were much more effective than were the unstimulated cultured cells, for which more than five times the number was required for the same suppressive activity. As far as the phenotypic proportion of helper (W3/13) and suppressor (OX-8) cells is concerned, we found no significant differences between the cultured cell groups and the freshly separated spleen cell group. The precise mechanism of these suppressive effects is the subject of further study. The transfer of TCGF-expanded cells appears to have a potent immunomodulatory effect.