CD4(+) (and not CD25+) T cells are the predominant interleukin-10-producing cells in the circulation of filaria-infected patients.
BACKGROUND
Interleukin (IL)-10 plays an important role in down-regulating the immune response to filarial parasites. The goal of this study was to characterize the predominant cellular source of IL-10 in human filarial infections.


METHODS
Multicolor flow cytometry was used to determine the frequencies of IL-10 production from various lymphocyte populations in the circulation of 23 patients with filarial infections and 8 uninfected control subjects.


RESULTS
The frequencies of cells spontaneously producing IL-10 was significantly greater in filaria-infected patients than in uninfected control subjects (geometric mean, 93 vs. 18 IL-10-producing cells/100,000 peripheral blood mononuclear cells; P = .03). Most IL-10-producing cells in filaria-infected patients were T cells, with CD4(+) and CD8(+) cells accounting for 48% and 27%, respectively, of all IL-10-producing cells; CD19(+) B cells, CD14(+) monocytes, and CD56(+) NK cells accounted for 10%, 8%, and 7%, respectively. Surprisingly, only 12% of the IL-10-producing CD3(+)CD4(+) cells were CD25(+). Seventy-seven percent of IL-10-producing CD4(+) T cells stained negatively for both IL-4 and interferon (IFN)-gamma, 22% were positive for IL-4, and <1% were positive for IFN-gamma.


CONCLUSIONS
These experiments demonstrate that the most frequent producers of IL-10 in human filarial infections are CD4(+) T cells, many of which are skewed toward a type 2 phenotype and most of which are not CD25(+).
Mitre
Edward
E
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA. emitre@usuhs.mil
Chien
Daniel
D
Nutman
Thomas B
TB
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism* / Q000469:parasitology*; D016022:Case-Control Studies; D005368:Filariasis / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism*; D053645:Interleukin-2 Receptor alpha Subunit; D010641:Phenotype
D053645:Interleukin-2 Receptor alpha Subunit; D016753:Interleukin-10