CD4(+) T cells specific to a glomerular basement membrane antigen mediate glomerulonephritis

Area of Science:

• Immunology
• Nephrology
• Pathology

Background:

• Antibody-mediated mechanisms were traditionally considered the primary drivers of glomerulonephritis (GN).
• Emerging evidence suggests a significant role for T cells in the pathogenesis of GN.

Purpose of the Study:

• To investigate the direct role of antigen-specific CD4(+) T cells in mediating glomerular injury.
• To elucidate the mechanisms by which T cells induce glomerulonephritis.

Main Methods:

• Generation of Th1 cell lines specific for the glomerular basement membrane (GBM) antigen Col4alpha3NC1.
• Transfer of activated T cells into naive rats to assess glomerulonephritis induction.
• Immunofluorescence microscopy to detect IgG and C3 deposition.
• Histopathological examination for crescent formation and T cell infiltration.
• Tracking of fluorescently labeled T cells in the kidney.

Main Results:

• Transfer of Col4alpha3NC1-specific T cells induced severe proteinuria/albuminuria in recipient rats.
• Histopathology revealed characteristic crescent-shaped lesions in glomeruli, indicative of GN, in a subset of recipients.
• No significant IgG or C3 deposition was detected in the glomeruli.
• T cells infiltrated the renal interstitium and were found concentrated in the kidney cortex, particularly in Bowman's space.

Conclusions:

• Antigen-specific CD4(+) T cells, specifically those targeting Col4alpha3NC1, can directly initiate and mediate glomerular injury, leading to glomerulonephritis.
• T cell-mediated GN may occur independently of significant antibody deposition.
• T cells accumulate in the kidney, targeting structures within or adjacent to Bowman's capsule.