Human proximal tubule epithelial cells modulate autologous B-cell function.

Area of Science:

• Immunology
• Nephrology
• Cell Biology

Background:

• B cells are rarely described in kidney inflammation outside of transplantation.
• In the kidney, B cells are found in the tubulointerstitium, interacting with proximal tubule epithelial cells (PTEC).
• Previously, activated PTEC were shown to modulate T lymphocyte and dendritic cell function.

Purpose of the Study:

• To investigate the interactions between activated proximal tubule epithelial cells (PTEC) and autologous B cells.
• To characterize how PTEC influence B cell phenotype, proliferation, and antibody production.

Main Methods:

• Activated human B cells were cultured with or without autologous PTEC.
• Assays included monitoring B cell proliferation, surface antigen expression (CD27), cytokine secretion, and antibody (Ab) production.
• Transwell and blocking studies (anti-PD-L1, sHLA-G, IDO) were used to identify mechanisms of interaction.

Main Results:

• PTEC significantly decreased B cell proliferation and CD27 expression.
• PTEC reduced the number of B cells secreting IgG and IgM, and overall Ab production.
• Interaction was primarily contact-dependent, with PD-L1 playing a key role; sHLA-G and IDO had minor effects.

Conclusions:

• Proximal tubule epithelial cells (PTEC) modulate autologous B cell phenotype and function.
• Mechanisms involve contact-dependent (PD-L1) and soluble factors (sHLA-G, IDO).
• These PTEC-B cell interactions may contribute to immune homeostasis in kidney inflammation.