Comparison of CD4 T-Cell Response in Plasmodium falciparum and vivax Malaria.

BACKGROUND

Plasmodium falciparum and vivax are parasites responsible for most malaria cases globally. In areas where these species coexist, individuals gain protection from P vivax more rapidly, and important biological differences between species may affect immune responses. CD4 T cells are key drivers of immunity to malaria as effector and helper cells, with T follicular helper cells having key roles in antibody development. Comparative studies on CD4 T cell responses between these species are limited.

METHODS

We assessed CD4 T cells in adults with either P falciparum or P vivax malaria. Activation and proliferation of CD4 T cells were measured ex vivo, and functional capacity was determined by intracellular cytokine staining via flow cytometry.

RESULTS

The phenotype, activation, and proliferation of CD4 T cell subsets were largely comparable between species. However, within the peripheral T follicular helper (pTfh) cell compartment, there was some evidence for species-dependent activation, with relatively increased pTfh1 cells in P falciparum infection. Additionally, in P falciparum, increased IL-10 production was detected, including within IL-21-producing CD4 T cells.

CONCLUSIONS

While activation and function of CD4 T cells in malaria are largely comparable, some species-dependent responses are detected within the pTfh-cell compartment that may affect antibody development.