Expansion of a CD26low Effector TH Subset and Reduction in Circulating Levels of sCD26 in Stable Allergic Asthma in Adults.

BACKGROUND AND OBJETIVE: The pathogenesis of asthma is dependent on the balance between regulatory and effector T cells, which display differential expression of CD25 and CD26. Therefore, alteration of circulating levels of sCD25 and sCD26 during allergic asthma could be conditioned by changes in leukocyte phenotype. Objectives: To analyze expression of CD25 and CD26 on T lymphocytes and their soluble derivatives (sCD25, sCD26) during stable phases of moderate-severe allergic asthma. METHODS: Cross-sectional study with 2 adult cohorts of allergic asthmatics. Clinical, anthropometric, pulmonary, hematological, and biochemical parameters were measured. Phenotyping was performed with flow cytometry in both circulating and cultured leukocytes. Dipeptidyl peptidase 4 (DPP4) activity was assayed in culture supernatants. RESULTS: In vitro studies revealed upregulation of CD26 on human T lymphocytes upon activation, especially under TH17-favoring conditions, and a correlation with soluble DPP4 activity (rs=0.641; P<.001). CD26 expression on lymphocytes was higher in asthmatics, while serum sCD26 was lower in women and patients. The latter finding could be associated with an expanded CD25low/CD26low/CD127low subset of effector CD4+ T cells in allergic asthma, with no changes in Treg percentages. However, women showed an increased Teff/Treg ratio, which could explain their greater susceptibility to asthma. CONCLUSIONS: Allergic asthma causes an increment in CD25lowCD26low helper T cells detected in stable stages. These changes are mirrored in serum and should be considered in the light of the downmodulating role of CD26 in major chemokines related to the pathogenesis of asthma such as CCL11 (eotaxin), CCL5 (RANTES), and CXCL12a (SDF-1α).

House dust mite species and allergen levels in Galicia, Spain: a cross-sectional, multicenter, comparative study.

BACKGROUND AND OBJECTIVES: Mites are important sources of allergens in Galicia, Spain. The objective of this study were to identify the main mite species and to determine allergen levels in mattresses from different locations in Galicia. MATERIAL AND METHODS: Dust samples were collected with a portable vacuum cleaner for 2 minutes from 2 m2 of the surface of the mattress used by mite allergic patients and controls. After collection, samples were immediatel frozen. Mite species were collected, identified, and counted, and the results expressed as mites per gram of dust. Mite allergen levels (Der p 1 and Der f 1) were measured using monoclonal antibodies. All individuals answered a questionnaire about the characteristics of their homes. RESULTS: A total of 332 dust samples were collected (112 from mite allergic patients and 220 from controls). Thirty-two species were identified. The mean age +/-SD of all the participants was 32.4 +/- 20.8 years and of the mattresses 7.6 +/- 5.9 years. The geometric mean of the total mite counts was 910.2 mites per gram (896.2 mites per gram in the mattresses of mite allergic patients and 917.3 in the mattresses of control subjects; P > .05). The main species was Dermatophagoides pteronyssinus, which was present in 97.6% of the samples (geometric mean, 584.7 mites per gram). The geometric mean level of Der p 1 was 13.1 microg/g of dust: 11.9 in the mattresses of mite allergic patients and 13.8 in the mattresses of control subjects. The geometric mean level of Der f1 was 1.1 microg/g: 1.5 in the mattresses of mite allergic patients and 0.8 in the mattresses of control subjects. Environmental risk factors associated with high mite counts included obvious signs of humidity in the bedroom and the age of the mattress. CONCLUSIONS: The mite fauna in Galicia is comprised of many species, several of which are known to be of allergologic importance. The total population is exposed to very high levels of mite allergens.