Surveillance of NK cell subsets and cytokine profile in patients with Rocky Mountain Spotted Fever

Abstract

The intracellular pathogen Rickettsia rickettsii causes tick-borne spotted fever (also called Rocky Mountain spotted fever (RMSF) and is increasingly recognized as an emerging cause of febrile illness in Mexico. However, little is known about the early immune responses to infection. Four RMSF pediatric patients on acute phase and eight healthy controls from Chihuahua, Mexico were recruited. The natural killer cell (NK) immunophenotype and the cytokine profile in peripheral blood were characterized by flow cytometry. The population of cytotoxic NK cells expressing NKG2D was significantly decreased in patients on 3rd day of hospitalization compared to the first sampling on admission. Interleukins IL-6, IL-8, and IL-10 levels were significantly increased in patients upon admission compared to controls. This study shows that circulating NK cells are numerically decreased, while cytokines induce a pro-inflammatory process in patients.