Figure 6.

Significant reduction of the human (h) CD4⁺ T-cell response to dominant-negative mutant class II transactivator (CIITA-DN) antigen-presenting cells. Expression of swine leucocyte antigen (SLA) class II (DR) on CD21⁺ B cells in peripheral blood mononuclear cells (PBMCs) from CIITA-DN (n = 4) and wild-type (WT) pigs (n = 6) was compared. (a) The expression of SLA class II (DR) on CD21⁺ B cells in CIITA-DN porcine (p) PBMCs was down-regulated compared with that on WT pPBMCs. Results are representative of four independent experiments. (b) There was significantly lower expression of SLA class II (DR) on CD21⁺ B cells from CIITA-DN pPBMCs than WT pPBMCs (**P < 0·01). (c) Human CD4⁺ T cells were co-cultured with CIITA-DN and WT (sibling with CIITA-DN pigs) pPBMCs (n = 6), and allogeneic hPBMCs (n = 6) for 6 days. The responses of hCD4⁺ T cells were measured by [³H]thymidine incorporation. As a negative control, hCD4⁺ T cells were cultured with autologus PBMCs (auto). There was a significantly lower hCD4⁺ T-cell response to CIITA-DN pPBMCs than to WT and allogeneic hPBMCs (**P < 0·01).