Regulatory activity of activated murine peripheral CD4(+)CD25(-) T cells: A possible mechanism of feedback regulation on adaptive immunity

This study was undertaken to investigate the possibility that peripheral CD4(+) CD25(-) T cells, once fully activated, transiently obtain suppressive function against other T cells. CD4(+) CD25(-) T cells, isolated from splenocytes of BALB/c mice, were stimulated with anti-CD3 MoAb in the presence of feeder cells for 72 h. The activated CD4(+) T cells (T-act) thus obtained were able to inhibit the activation and proliferation of bystander CD4(+) T cells in a non-MHC- restricted manner. T-act-mediated suppression was cell contact dependent, reversible by exogenous IL-2 as well as anti-GITR antibody. Furthermore, adoptive transfer of Tact cells significantly downregulated humoral response of BALB/c mice to s.c. immunization with ovalbumin. We argue that suppression ;mediated by activated CD4(+) CD25(-) T cells may play an important role in maintaining homeostasis of the immune system and preventing excessive T-cell responses in vivo.ImmunologySCI(E)PubMed3ARTICLE5500-5066