T cell exhaustion in Giardia intestinalis infection: A review

Giardiasis, caused by the protozoan parasite Giardia intestinalis, is a gastrointestinal infection responsible for approximately 280 million cases of gastroenteritis worldwide each year. While T cells are crucial in the host's defence against G. intestinalis, it is unclear which T cell subsets actively help control the infection.

This review aims to synthesise existing literature on the relationship between T cell exhaustion and giardiasis, examine the T cell subsets affected, identify diagnostic markers that reflect the severity of Giardia infection, and explore potential vaccine development.

A comprehensive database search from Google Scholar and Medline/PubMed identified eligible studies that reported on T cell exhaustion markers, immune response and giardiasis. Search terms included "Giardia", "Giardiasis", "T cells" and "T cell exhaustion". Articles were reviewed for data on T-cell function, cytokine expression, and immune responses in people with giardiasis.

T cell exhaustion is common in giardiasis, as indicated by the findings. There are higher proliferation rates and upregulation of surface activation markers in CD4 cells in Giardia infection. Natural regulatory T cell levels (CD4+, CD25+, and Foxp3+) are significantly increased in Giardia infection. Chronic giardiasis and co-morbidity contribute to T-cell exhaustion.

The activation and proliferation of T cells are key to the clearance of Giardia infection. Most cytokine profiles are markedly elevated during Giardia infection. Cytokine responses vary depending on host immunity and parasite load. Understanding the roles of cytokines in both T-cell and B-cell-mediated immunity could guide treatment protocols and control measures.