Cryptococcus neoformans differently regulates B7-1 (CD80) and B7-2 (CD86) expression on human monocytes

Area of Science:

• Immunology
• Microbiology
• Cellular Biology

Background:

• T cell activation requires two signals from antigen-presenting cells (APCs): antigen-specific (TCR-MHC) and co-stimulatory (B7-CD28/CTLA-4).
• B7-1 and B7-2 are crucial co-stimulatory molecules on APCs that regulate T cell responses.

Purpose of the Study:

• To investigate how encapsulated and acapsular Cryptococcus neoformans and Candida albicans modulate B7-1 and B7-2 expression on human monocytes.
• To analyze the role of B7-1 and B7-2 in T cell activation during fungal infections.

Main Methods:

• Human monocytes were exposed to encapsulated/acapsular C. neoformans or C. albicans.
• Expression of B7-1 and B7-2 molecules was analyzed using kinetic studies.
• The impact of co-stimulatory molecules on T cell proliferation was assessed.

Main Results:

• C. albicans and acapsular C. neoformans induced B7-1 expression, while encapsulated C. neoformans was a poor stimulator.
• Acapsular C. neoformans and C. albicans modestly increased B7-2 expression; encapsulated C. neoformans did not.
• B7-1 expression peaked at 24-48 hours; opsonic antibody enhanced B7-1 but not B7-2 expression.
• T cell proliferation was substantially inhibited, indicating fungal interference with co-stimulatory molecule function.

Conclusions:

• Fungi, particularly encapsulated C. neoformans, can interfere with the regulation of co-stimulatory molecules (B7-1, B7-2).
• This interference may contribute to the impaired inflammatory responses observed in C. neoformans infections.
• Understanding fungal modulation of co-stimulatory molecules offers insights into immune evasion strategies.