Soluble granzyme B and cytotoxic T lymphocyte activity in the pathogenesis of systemic lupus erythematosus

Activated cytotoxic T lymphocyte (CTL) mediated target cell death has been implicated in the development of systemic autoimmune disease like SLE. However, the role of soluble granzyme B and its relationship with CTL activity and disease activity is still unknown. In this study, we evaluated role of soluble granzyme B and cytotoxic T lymphocyte activity in SLE patients. The soluble granzyme B was measured in the serum by an enzyme-linked immunosorbent assay while cytotoxic T lymphocyte activity was measured by flow cytometry. The disease activity was determined by using SLE Disease Activity Index (SLEDAI) score. Cytotoxic T lymphocyte activity was increased and strongly associated with disease activity. The soluble granzyme B levels were higher in SLE patients and associated with various clinical features like reduced complement components; C3 & C4 and skin lesion. The soluble granzyme B levels were also sturdily related with severity of the disease. The findings of this study suggest that excessive secretion of soluble granzyme B and enhanced activity of cytotoxic T lymphocyte may play a vital role in the pathogenesis of SLE and organ damage. Also, evaluation of soluble granzyme B may be helpful in monitoring the clinical features associated with activated CTL in SLE.

► Increased levels of soluble granzyme B were associated with various clinical parameters like decreased level of complement proteins; C3 & C4. ► Increased levels of soluble granzyme B were associated with skin lesion in SLE patients. ► Activated cytotoxic T lymphocytes were associated with severity of disease in SLE patients. ► Excessive secretion of soluble granzyme B and enhanced activity of CTL may play a vital role in the pathogenesis of SLE and organ damage. ► Also, evaluation of soluble granzyme B may be helpful in monitoring the clinical features associated with activated CTL in SLE.