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We attempted to elucidate the mechanism of action of T cell growth factor (TCGF)-expanded cells after stimulation with concanavalin A (Con A), a process which reduces the severity of adjuvant arthritis (AA), as seen in transferred syngeneic rats. TCGF-expanded cells were fractionated by Percoll density gradient or by the panning method, before the transfer. Transfer of cells with a density of between 1070 and 1079 suppressed AA most effectively, compared with other fractions with a density of less than 1070. A large number of the cells with density 1070-1079 were of the W3/25 phenotype. The transfer of W3/25 positive cells obtained by the panning method from TCGF-expanded cells reduced AA but not W3/25 negative cells. The suppressor function of TCGF-expanded cells was examined in an assay system in vitro. The addition of Con A-stimulated cells to the assay culture (but not expanded with TCGF), suppressed both the proliferation of spleen cells stimulated with Con A and the IgG production stimulated with lipopolysaccharide. The addition of TCGF-expanded cells to the assay culture had no effect on these responses. Thus, the W3/25 cells in the TCGF-expanded cells seem to function as suppressor-inducer cells, affect the presuppressor cells of the recipient rat and differentiate to suppressor effector cells. [ABSTRACT FROM AUTHOR]

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 ll collagen in incomplete Freund's adjuvant for induction of collagen induced arthritis (CIA) on day 0. Each of 5×107 cultured cells without mitogenic stimulation. 2 ×107 Con A-stiniuIated cells, or 1 ×107 TCGF-expanded cells cultured for 8 days (4 days × 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 lo 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 ×107 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 phenotypie 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. [ABSTRACT FROM AUTHOR]

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 × 107 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 × 107 spleen cells proved to be the optimal dose for suppressing AA, and transfer of less than 2 × 107 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. [ABSTRACT FROM AUTHOR]