Reduced Type 2 Innate Lymphocyte Cell Frequencies in Patent Wuchereria bancrofti-Infected Individuals

Approximately 51 million individuals suffer from lymphatic filariasis (LF) caused mainly by the filarial worm Wuchereria bancrofti. Mass drug administration (MDA) programs led to a significant reduction in the number of infected individuals, but the consequences of the treatment and clearance of infection in regard to host immunity remain uncertain. Thus, this study investigates the composition of myeloid-derived suppressor cells (MDSCs), macrophage subsets and innate lymphoid cells (ILCs), in patent (circulating filarial antigen (CFA)+ microfilariae (MF)+) and latent (CFA+MF-) W. bancrofti-infected individuals, previously W. bancrofti-infected (PI) individuals cured of the infection due to MDA, uninfected controls (endemic normal (EN)) and individuals who suffer from lymphoedema (LE) from the Western Region of Ghana. Frequencies of ILC2 were significantly reduced in W. bancrofti-infected individuals, while the frequencies of MDSCs, M2 macrophages, ILC1 and ILC3 were comparable between the cohorts. Importantly, clearance of infection due to MDA restored the ILC2 frequencies, suggesting that ILC2 subsets might migrate to the site of infection within the lymphatic tissue. In general, the immune cell composition in individuals who cured the infection were comparable to the uninfected individuals, showing that filarial-driven changes of the immune responses require an active infection and are not maintained upon the clearance of the infection.