In vivo studies with mTregitopes. IL-4 and antibody responses to HDM lysate and dust mite antigen are shown. Purified HDM antigen DerP2 is a component of HDM lysate. HLA DR4 transgenic mice were immunized 3 times with (1) HDM lysate alone, (2) HDM lysate plus Tregitope 289, or (3) sham control. In an additional arm, mice were first pre-sensitized to HDM lysate by 3 weekly injections followed by 3 additional weekly injections of an equal mixture of HDM lysate plus Tregitope 289. HDM lystate immunization (■) provokes a robust response by as assessed by IL-4 ELISpot (A) and anti HDM Antigen antibody titers (B). These responses are both significantly reduced (▩) when HDM lysate is coadministered with the murine homologue of Tregitope 289. Responses to HDM lysate in sham-immunized animals are negative, as expected. Antibody response (B) and IL-4 ELISpot (A) are correlated. Panel A shows 38% suppression of ELISpot response in HDM-naive mice (P < .001) and 84% in the case of HDM presensitized mice (P < .001). Panel B shows 61% suppression of HDM antigen antibody response in HDM-naive mice (P = .138); ELISA was not performed for HDM-presensitized mice. Error bars indicate SD.