Immunophenotyping of Granzyme-B expressing lymphocyte subset in renal allograft recipients with Chronic Allograft Dysfunction

Abstract

Background: Granzyme-B is a serine proteinase expressed and released mainly by the cytotoxic T and NK cell. Granules intact Granzyme-B is directly delivered into the target cell, while extracellular Granzyme-B, released in serum leads to nonspecific cleavages of extracellular matrix molecules like vitronectin, collagen, TGF-β, IL-1 and invites systemic inflammation, tissue remodeling and fibrosis leading to the development of chronic renal allograft dysfunction.

Objective: We aimed to immunophenotype the Granzyme-B positive lymphocyte subset and Granzyme-B role in the development of chronic renal allograft dysfunction.

Methods: We have analyzed the Granzyme-B+ CD8T/CD8^neg and Granzyme-B⁺CD3⁺/CD3^neg cell subset by the flowcytometry and serum Granzyme-B level by the enzyme-linked immunosorbent assay.

Results: We have found that the frequency of Granzyme-B⁺ CD8^neg CD3⁺T cell, Granzyme-B⁺ CD8^lowCD3⁺T cell and Granzyme-B⁺ CD8^high CD3⁺T cell subset was significantly lower and serum Granzyme-B level was significantly higher in CAD group. The frequency of CD3⁺T, CD3^neg lymphocyte, CD8^neg CD3⁺T, CD8^lowCD3⁺T, CD8^high CD3⁺T, Granzyme-B⁺CD3^negCD8^neg lymphocyte was similar between the group. The frequency of CD3⁺CD8^negGzm-B⁺ cell was negatively correlated with serum creatinine and CD3⁺CD8^highGzm-B⁺ cell was negatively correlated with serum Granzyme-B level. Similarly, Serum Granzyme-B level was positively correlated with serum creatinine, urine proteinuria and negatively with eGFR.

Conclusion: Allostimulated CD8⁺T lymphocyte cell subset releases their Granzyme-B in serum extracellularly, which may mediate the inflammation, allograft fibrosis and chronic allograft dysfunction in renal allograft recipient patients.