TofBs show regulatory capacity and suppress the proliferation of naive T-cells. Differentially primed T cells were added to in vitro cocultures of naive, CFSE-labeled CD4+ T cells and mature DCs loaded with antigenic pOVA. At 72 hours, proliferation of the naive T cells was determined by FACS. (A) Upon addition of TofBs but not of TofDCs, proliferation of naive T cells determined by CFSE-dilution is markedly inhibited. Equal numbers of cells (105) were used. No proliferation is observed when naive T cells are cultured in the absence of DCs. (B) The regulatory effect of TofBs can be titrated. When TofBs were added at a ratio of 3:1 to naive T cells, the effect was more pronounced. At a ratio of 0.03:1, minor effects can be seen. In contrast, TofDCs do not show inhibition even at a 3:1 ratio over naive T. (C) The inhibitory effect can only be observed after B-cell loading with specific peptide (pOVA) but not with complete protein (Ovalbumin). The data shown are representative of 2 (panel B) to 5 (panels A,C) independent experiments. Dots represent the mean plus or minus SD.
