Methods: PBMC were isolated from whole blood taken from 6 peanut allergic individuals and labeled with CellTrace Violet Dye prior to the addition of crude peanut extract (CPE) in the presence or absence of GLA. After 6d, supernatants were collected for multiplexed cytokine measurement and the cells analyzed for both CD4+T cell proliferation and intracellular cytokine profile by flow cytometry.
Results: CPE-induced proliferation of CD4+ T cells was significantly inhibited in the presence of GLA (10.70% with CPE alone vs. 3.42% with CPE plus 3mg/ml GLA, p = 0.003). In addition, the presence of GLA inhibited the CPE- induced IL-13 response (28.04pg/ml with CPE alone vs. 9.56 pg/ml with CPE plus 3mg/ml GLA, p < 0.05). This reduction in IL-13 was paralleled by enhancement of the IFNγ response (344.90 pg/ml with CPE alone vs. 4798.00 pg/ml for CPE plus 3mg/ml GLA, p<0.05). In addition, IL-10 levels were increased in the presence of GLA (28.96 pg/ml with CPE alone vs. 213.70 pg/ml with CPE plus 3mg/ml GLA, p<0.05).
Conclusions: Our results demonstrate that the TLR4 agonist GLA can redirect Th2-type responses to peanut antigens toward Th1-type responses, in vitro, supporting the proposed mechanism of action for GLA.