title: Role of immunoglobulin G subclasses in Q fever.
abstract: The progression of Q fever to either acute or chronic disease has been attributed both to biological characteristics of the bacteria and to the host immune response. In order to determine whether a specific immunoglobulin G (IgG) subclass distribution could play a diagnostic or prognostic role in Q fever, IgG subclass levels were measured in patients with acute or chronic disease. It was observed that (i) IgG1 and IgG3 levels were elevated in patients with chronic Q fever compared to patients with acute disease or normal controls; (ii) variations over time reflected inverse complementary relationships of subclass levels, such as between IgG1 and IgG3 compared with IgG2 and IgG4, or an inverse relationship between IgG1 and IgG2; (iii) variations in IgG2 and IgG3 total subclass levels during follow-up of patients with chronic Q fever showed a decrease in IgG2 with a concomitant increase in IgG3 two years from disease onset. These findings indicate that measurements of IgG subclasses may be a simple, additional tool useful in the diagnosis of Q fever. This data raises the question of an unusual immunoregulatory mechanism in Q fever that is implicated in the presentation of the clinical disease.
authors.affiliation: Centro Nacional de Microbiología, Virología e Inmunología Sanitarias, Madrid, Spain.
authors.forename: M T
authors.initials: MT
authors.lastname: Camacho
authors.forename: I
authors.initials: I
authors.lastname: Outschoorn
authors.forename: A
authors.initials: A
authors.lastname: Tellez
mesh_terms: D000208:Acute Disease; D002908:Chronic Disease; D016997:Coxiella burnetii / Q000276:immunology; D018450:Disease Progression; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007142:Immunoglobulin gamma-Chains / Q000032:analysis* / Q000097:blood / Q000276:immunology; D011778:Q Fever / Q000175:diagnosis / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D007142:Immunoglobulin gamma-Chains