title: Elevated anti-malarial IgE in asymptomatic individuals is associated with reduced risk for subsequent clinical malaria.
abstract: Immunological characteristics were assessed for prospective risk of clinical malaria in a longitudinally followed population in a holoendemic area of Tanzania. Baseline characteristics including crude Plasmodium falciparum extract-specific IgE and IgG; total IgE; and parasitological indices, e.g. number of P. falciparum clones, were investigated among 700 asymptomatic individuals. Cox regression analysis estimated the risk of succumbing to a new clinical episode during a 40 weeks follow up. High anti-P. falciparum IgE levels were associated with reduced risk of acute malaria in all age groups independently of total IgE levels. Statistically significant reduced odds ratio of 0.26 (95% CI, 0.09-0.72, P=0.010) and 0.44 (95% CI, 0.19-0.99, P=0.047) for the two highest fifths, respectively was observed after adjustment for age, sex, total IgE, numbers of parasite clones per infection and HIV-1 seropositivity. In contrast, high levels of malaria specific IgG or total IgE were not associated with reduced risk to succumb to a new clinical episode. A protective effect of asymptomatic multiclonal P. falciparum infections was also confirmed. For the first time, anti-malarial IgE levels in asymptomatic individuals in endemic area are found to be associated with reduced risk for subsequent malaria disease. Specific IgE antibodies may play role in maintaining anti-malarial immunity, or indicate other aspects of immune function relevant for protection against malaria.
authors.affiliation: Infectious Diseases Unit, Karolinska University Hospital, Karolinska Institutet, S-171 76 Stockholm, Sweden. sandor.bereczky@medks.ki.se
authors.forename: Sándor
authors.initials: S
authors.lastname: Bereczky
authors.forename: Scott M
authors.initials: SM
authors.lastname: Montgomery
authors.forename: Marita
authors.initials: M
authors.lastname: Troye-Blomberg
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Rooth
authors.forename: Marie-Anne
authors.initials: MA
authors.lastname: Shaw
authors.forename: Anna
authors.initials: A
authors.lastname: Färnert
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D007223:Infant; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology; D015995:Prevalence; D011379:Prognosis; D012008:Recurrence; D012307:Risk Factors; D013636:Tanzania / Q000453:epidemiology
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D007073:Immunoglobulin E