CD160 and HVEM antibodies specifically enhance IFNγ production by CD4 T-cells in response to the Tetanus toxoid recall antigen. A) IFNγ production by total PBMCs (1.5 × 106 cells/ml) stimulated with 2.5 μg/ml of Tetanus toxoid in the presence or absence of anti-CD160 clone CL1-R2 mAb (left panel), HVEM pAb (right panel) or their matched isotype control Abs (n = 10). IFNγ was measured by ELISA from the supernatant following 5 days of stimulation. B) Left panel: Surface staining of cells using anti-CD3, anti-CD4, anti-CD8, anti-CD25 and anti-CD134 (OX40) analyzed by FACS (gating on CD3+ lymphocytes followed by gating on either CD4+ or CD8+ T-cells). Right Panel: analysis of the frequency of CD25+CD134+ double positive CD4+ and CD8+ T-cell populations (n = 5). P values were determined using the nonparametric Kruskal-Wallis and Dunn’s post-test.