Major expansion of γδ T lymphocytes following cytomegalovirus infection in kidney allograft recipients

In normal persons, circulating gamma delta T cells comprise a minor cell subset (0.5%-6% of total lymphocytes), gamma delta T cells were studied in the context of therapeutic immunosuppression in transplanted patients. Flow cytometry detected an expansion of gamma delta T cells in 31 of 205 renal allograft recipients and in 2 of 41 uremic patients but in none of 45 healthy subjects. Univariate statistical analysis identified cytomegalovirus (CR;IV) infection (P<.001), second graft (P<.001), and antithymocyte globulin treatment (P=.01) as three variables associated with high levels (greater than or equal to 6%,) of circulating gamma delta T cells in allograft recipients. Multivariate analysis further indicated that CMV infection was the only independent parameter associated with >6% gamma delta T cells, gamma delta T cell expansion directly followed CMV infection and was never observed in persons who did not develop CMV infection. Thus gamma delta T cells may represent a first-line defense mechanism against CR-IV infection in a person whose alpha beta T cell response has been weakened by immunosuppression.