Altered Lymphocytes in Chronic Fatigue Syndrome

Authors: Isabel Barao, Ph.D., Daniel Peterson, M.D., Dorothy Hudig, Ph.D;

Presentation format: Oral or Poster
Corresponding author: isilvestre@medicine.nevada.edu
Title: Altered Distribution of Lymphocyte Populations in Chronic Fatigue Syndrome Patients
Authors: Isabel Barao, Ph.D., Daniel Peterson, M.D., Dorothy Hudig, Ph.D
Institutional Affiliations: University of Nevada, Reno, School of Medicine, Simmaron Research, Inc., Sierra Internal Medicine
Key Words: CFS, NK cells, T cells, cytotoxicity, viral infections

Objective: The goal of our research is to define immunologic deficiencies of patients with chronic fatigue syndrome (CFS) and ultimately to improve the health of these patients by increasing their immunity. Setting:CFS is a debilitating disease of unknown cause(s) defined by the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. Our patient population is the well-known Reno-Lake Tahoe CFS cohort. Methods: Peripheral blood is the site of traffic of lymphocytes with varying roles in immunity. Lymphocytes are circulating so as to be available to fight infections anywhere in the body or trafficking into secondary lymphoid organs where the lymphocytes will proliferate and differentiate.There are different types of lymphocytes in the blood [including helper T cells, cytotoxic T cells, T cells, B cells, natural killer (NK), and NK-T cells]. Alterations in these populations from healthy individuals are a hallmark of immune stress. To profile these populations, we used flow cytometry with fluorescent antibodies to identify the different populations of lymphocytes in the peripheral blood of CFS patients. Results: We found unusual increases in a 'hybrid' population of lymphocytes in CFS patients. This population has features of both T cells and NK cells and is normally 1-5% of all lymphocytes but can be as high as 30% in the CFS patients. Interpretation: The results are consistent with altered immunity in CFS patients, particularly altered immune responsesto chronic viral infections. Further characterization, including repeated tests of the same patients, is needed to determine if this unusual population is persistent and to determine if it can mediate cytotoxicity towards virally infected cells.