Frequent IgG subclass and mannose binding lectin deficiency in patients with chronic fatigue syndrome

Abstract

Chronic fatigue syndrome (CFS) is a severe disease characterized by various symptoms of immune dysfunction. CFS onset is typically with an infection and many  patients suffer from frequently recurrent viral or bacterial infections.  Immunoglobulin and mannose binding lectin (MBL) deficiency are frequent causes  for increased susceptibility to infections. In this study we retrospectively  analysed 300 patients with CFS for immunoglobulin and MBL levels, and B-cell  subset frequencies. 25% of the CFS patients had decreased serum levels of at  least one antibody class or subclass with IgG3 and IgG4 subclass deficiencies as  most common phenotypes. However, we found elevated immunoglobulin levels with an  excess of IgM and IgG2 in particular in another 25% of patients. No major  alteration in numbers of B cells and B-cell subsets was seen. Deficiency of MBL  was found in 15% of the CFS patients in contrast to 6% in a historical control  group. In a 2nd cohort of 168 patients similar frequencies of IgG subclass and  MBL deficiency were found. Thus, humoral immune defects are frequent in CFS  patients and are associated with infections of the respiratory tract.