Cytomegalovirus aggravates the autoimmune phenomenon in systemic autoimmune diseases

Background: Human Cytomegalovirus (CMV), because of its ability to extensively manipulate host immunity during active infection, has been suggested to be involved in autoimmunity. However, its influence on T-cells and cytokines in systemic autoimmune diseases like systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) is indistinct. Methods: We investigated the in-vitro response of T lymphocytes from SLE and SSc patients to CMV antigen. Functional activity of T lymphocytes was determined by estimating Th1 (IL-2 and IFN-γ) and Th2 (IL-4 and IL-10) cytokines. Results: We observed that CMV antigen stimulation in-vitro resulted in significant increase in CD4:CD8 T-cell ratio in peripheral blood mononuclear cells (PBMCs) from SLE and SSc patients; response dominated by CD4⁺ than CD8⁺ memory T-cells. SSc T-cell response was differentiated by aberrant increase in CD4⁺CD25⁺ T-cells. CMV antigen caused elevation in IL-4 and IFN-γ production in both patient PBMCs, whereas IL-2 was also raised in SLE PBMCs. The development of large pool of memory T-cells and overproduction of IFN-γ may result in flare-up of autoimmunity in these patients. Conclusion: Our study provides an insight into the immunopathological potential of CMV-reactive immune cells to develop new potential strategies for targeted therapeutic intervention.