Intragraft T cell receptor transcript expression in human renal allografts

Area of Science:

• Immunology
• Transplantation Science
• Molecular Biology

Background:

• Allograft rejection is a T cell-mediated immune response.
• The specific T cell populations involved in rejection (monoclonal vs. polyclonal) remain unclear.
• Previous studies on T cell receptor (TCR) heterogeneity in rejection have yielded conflicting results.

Purpose of the Study:

• To investigate whether allograft rejection is mediated by a limited number of T cell clones or a polyclonal T cell population.
• To analyze T cell receptor (TCR) heterogeneity in kidney transplant biopsies.
• To correlate TCR diversity with the presence and type of allograft rejection.

Main Methods:

• Utilized reverse transcription-assisted polymerase chain reaction (PCR) on kidney transplant biopsy RNA.
• Quantified T cell infiltration using TCR beta chain constant region (C beta) and glyceraldehyde phosphate dehydrogenase (GAPD) gene expression.
• Examined TCR heterogeneity by amplifying 22 variable region genes of the TCR beta chain (V beta).

Main Results:

• T cell infiltration was significantly higher in acute cellular rejection (ACR) compared to nonrejection (NR).
• The number of intragraft V beta families was elevated in both acute and chronic rejection phases versus nonrejection.
• Serial biopsies showed an increase in intragraft V beta families during progression to immunologic graft loss.

Conclusions:

• Increased numbers of TCR V beta families in rejecting grafts support a polyclonal T cell infiltration hypothesis.
• Clinically apparent allograft rejection is associated with a diverse, polyclonal T cell response.
• This finding has implications for understanding rejection mechanisms and developing targeted therapies.