Human Memory CD4+ T Cell Immune Responses against Giardia lamblia

Area of Science:

• Immunology
• Infectious Diseases
• Microbiology

Background:

• Giardia lamblia causes diarrheal illness or asymptomatic infections.
• T cells are crucial for immune responses to Giardia, with potential long-lasting memory.
• Recent animal studies suggest a role for TH17 responses in Giardia infection.

Purpose of the Study:

• To characterize human CD4(+) T cell responses to Giardia lamblia.
• To investigate the role of specific cytokines, including IL-17A, in the human immune response to giardiasis.

Main Methods:

• Peripheral blood mononuclear cells (PBMCs) from giardiasis patients and healthy controls were stimulated with Giardia antigens.
• Flow cytometry measured cytokine production (TNF-α, IFN-γ, IL-17A, IL-10, IL-4) in CD4(+) effector memory T cells.
• T cell activation, proliferation, and cytokine levels in supernatants were assessed after 6 days of culture.

Main Results:

• Individuals with giardiasis showed significantly increased IL-17A-producing CD4(+) EM T cells after 24 hours of stimulation.
• Elevated levels of IL-17A and TNF-α co-producing cells were observed in Giardia-exposed individuals.
• Giardia antigen stimulation led to increased inflammatory cytokines, CD4(+) T cell activation, and proliferation in patients.

Conclusions:

• Symptomatic Giardia infection in humans elicits a CD4(+) effector memory T cell response.
• Interleukin-17A (IL-17A) production is a significant component of this human immune response to Giardia.