A High Frequency of HIV-Specific Circulating Follicular Helper T Cells Is Associated with Preserved Memory B Cell...

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Follicular helper T cells (Tfh) are vital for effective antibody production.
• Understanding the role of Tfh cells in spontaneous HIV control is crucial for developing therapeutic and vaccine strategies.
• HIV controllers offer a unique model to study natural viral control mechanisms.

Purpose of the Study:

• To investigate the phenotype and function of circulating Tfh (cTfh) cells in individuals who naturally control HIV-1 replication.
• To compare HIV-specific cTfh cells in controllers versus treated HIV patients with low viral loads.
• To determine the contribution of cTfh cells to the humoral immune response in controlled HIV infection.

Main Methods:

• Analysis of circulating Tfh (cTfh) cell phenotype and function in HIV controllers and treated patients.
• Detection of HIV-specific cTfh cells using Gag-MHC-II tetramer labeling.
• Assessment of PD-1 expression on cTfh cells.
• Functional assays measuring IgG secretion by B cells in co-culture with cTfh cells.

Main Results:

• HIV-specific cTfh cells were significantly more frequent in HIV controllers compared to treated patients.
• PD-1 expression intensity was higher on Tfh cells from treated patients, indicating persistent immune activation.
• cTfh cells from controllers were more efficient in inducing HIV-specific IgG production.
• The frequency of HIV-specific cTfh cells strongly correlated with HIV-specific IgG production.

Conclusions:

• Preserved cTfh-B cell interactions contribute to robust memory B cell responses in controlled HIV infection.
• Tfh cell-mediated help plays an underappreciated role in spontaneous HIV control.
• Inducing Tfh cell help may be a critical component of future HIV vaccine strategies aimed at achieving persistent B cell responses.