Intraepithelial and stromal lymphocytes in the normal human prostate

Area of Science:

• Urology
• Immunology
• Pathology

Background:

• The distribution and role of lymphocytes in the healthy human prostate are not well understood.
• Lymphocytes may influence immune responses, potentially impacting prostate hyperplasia and cancer development.

Purpose of the Study:

• To investigate the distribution and types of lymphocytes within the normal human prostate.
• To determine if lymphocyte distribution varies with patient age, race, or anatomical location within the prostate.

Main Methods:

• Studied 28 normal autopsy prostates (ages 1-64), excluding those with hyperplasia, neoplasia, cancer, or prostatitis.
• Used immunohistochemistry to stain for CD20 (B cells), CD45 (all leukocytes), CD45RO (memory T cells), CD4 (helper T cells), and CD8 (cytotoxic T cells).
• Quantified lymphocytes in stromal and epithelial compartments across peripheral, transition, and central zones.

Main Results:

• Stromal lymphocytes were significantly more numerous than epithelial lymphocytes (7.32 vs 2.04 cells/mm²).
• The majority of lymphocytes were T cells (CD45RO+), with CD4+ T cells predominant in the stroma and CD8+ T cells in the epithelium.
• Lymphocyte counts did not differ significantly by age, race, or prostate zone, though peripheral zones showed a trend towards higher counts.

Conclusions:

• Prostate immune response is primarily cell-mediated, dominated by T cells.
• Lymphocyte distribution is consistent across demographic factors and anatomical zones.
• The higher concentration of cytotoxic/suppressor T cells (CD8+) within the epithelium suggests a role in defending against pathogens entering via retrograde flow.