Depressed adjuvant arthritis in rats transferred with spleen cells from Trypanosoma cruzi-infected syngeneic donors.

In the present study we investigated whether the attenuating effect of chronic Trypanosoma cruzi (Tc) infection on adjuvant arthritis (AA) in the rat could be transferred to naive recipients. Transfer of whole spleen cells, but not of serum, from Tc-infected rats reduced AA (means +/- SEM: 11 +/- 0.5) in recipient animals (control values, means +/- SEM: 19 +/- 0.7). Transfer of a T-cell-enriched subpopulation from spleen cells of Tc-infected rats (obtained by filtration through a nylon wool column) resulted in a similar attenuation of AA (means +/- SEM: 7.5 +/- 2.2). The arthritic response of rats intraperitoneally inoculated with 2 x 10(5) Tc 48 h before induction did not differ from that observed in controls. Neither parasites nor specific antibodies were observed in suckling mice inoculated with serum or cell suspensions employed in transfer experiments. Consequently, the depressive effect on AA could not be directly attributed to Tc per se. We hypothesize that a homeostatic immunosuppressor mechanism may be responsible for this phenomenon.