Filarial Lymphedema Patients Are Characterized by Exhausted CD4 + T Cells.

Worldwide, more than 200 million people are infected with filariae which can cause severe symptoms leading to reduced quality of life and contribute to disability-adjusted life years (DALYs). In particular, lymphatic filariasis (LF) caused by Wuchereria bancrofti can lead to lymphedema (LE) and consequently presents a serious health problem. To understand why only a fraction of the infected individuals develop pathology, it is essential to understand how filariae regulate host immunity. The central role of T cells for immunity against filariae has been shown in several studies. However, there is little knowledge about T cell exhaustion, which causes T cell dysfunction and impaired immune responses, in this group of individuals. Recently, we showed that LE patients from Ghana harbor distinct patterns of exhausted effector and memory CD8 ⁺ T cell subsets. Based on these findings, we now characterized CD4 ⁺ T cell subsets from the same Ghanaian patient cohort by analyzing distinct markers within a 13-colour flow cytometry panel. We revealed that LE patients had increased frequencies of CD4 ⁺ T cells expressing exhaustion-associated receptors such as KLRG-1, TIM-3 and PD-1 compared to healthy endemic normal and W. bancrofti -infected individuals. Moreover, CD4 ⁺ T cells in LE patients were characterized by distinct co-expression patterns of inhibitory receptors. Collectively with the previous findings on CD8 ⁺ T cell exhaustion patterns, the data shown here demonstrates that filarial LE patients harbor distinct subsets of exhausted T cells. Thus, T cell exhaustion patterns in LE patients need attention especially in regards to susceptibility of concomitant infections and should be taken into consideration for LE management measures.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2022 Horn, Ritter, Arndts, Borrero-Wolff, Wiszniewsky, Debrah, Debrah, Osei-Mensah, Chachage, Hoerauf, Kroidl and Layland.)