Hyperplastic lymphoid tissue in HIV/AIDS: an electron microscopic study.

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Human immunodeficiency virus (HIV) establishes persistent infection in lymphoid tissues.
• Follicular dendritic cells (FDC) within germinal centers (GC) are implicated in HIV association, but productive infection is debated.
• Gastrointestinal tract-associated lymphoid tissue (GALT) role in HIV persistence is less understood.

Purpose of the Study:

• To ultrastructurally characterize lymphoid tissues in HIV/AIDS patients.
• To evaluate lymphoid tissue, particularly GALT, as a reservoir and source of HIV.
• To determine if FDC are productively infected by HIV.

Main Methods:

• Transmission electron microscopy (TEM) was used to examine lymph nodes, tonsils, and gastrointestinal biopsies.
• Samples were fixed in neutral buffered glutaraldehyde.
• Immunohistochemistry (IHC) and in situ hybridization (ISH) were referenced from prior studies.

Main Results:

• Mature HIV particles were abundant in the GC of hyperplastic lymph nodes, tonsils, and GALT, enmeshed in the FDC network.
• HIV particles were observed budding from both FDC and lymphocytes, confirming productive infection.
• The highest viral loads were found in untreated individuals and lymph nodes co-infected with opportunistic pathogens like Mycobacterium avium complex.

Conclusions:

• Ultrastructural analysis confirms FDC are productively infected by HIV in lymph nodes, tonsils, and GALT.
• Lymphoid tissues, especially hyperplastic ones, serve as a significant reservoir and source of HIV.
• The FDC network plays a crucial role in harboring and potentially spreading HIV within the body.