Measuring the Immune Memory Response of In Vitro Polarized Th1, Th2, and Th17 Cells in the Face of OVA Transgenic Leishmania major in Mouse Model

Th1 and Th2 cytokines determine the outcome of Leishmania major infection and immune protection depends mainly on memory T cells induced during vaccination. This largely hinges on the nature and type of memory T cells produced. In this study, transgenic Leishmania major expressing membrane associated ovalbumin (mOVA) and soluble ovalbumin (sOVA) are used as a model to study whether fully differentiated Th1/ Th2 &Th17 cells can recall immune memory and tolerate pathogen manipulation. Naive OT-II T cells were in vitro polarised into Th1/Th2, and these cells were transferred adoptively into recipient mice. Following transferring the memory cells, recipient mice were challenged with OVA transgenic Leishmania major and wild type parasite was used a control. The in vitro polarised T helper cells continued to produce the same cytokine signatures after challenged by both forms of OVA-expressing Leishmania major parasites in vivo. This suggests antigen-experienced cells cells remain the same or unaltered in the face of OVA transgenic Leishmania major. Such ability of the antigen-experienced cells to remain resilient to manipulation by the parasite signifies that vaccines might be able to produce immune memory responses and withstand against the parasite immune manipulation and protect the host from infection.