Assay of IL-22 and IL-25 in serum, whole blood, and peripheral blood mononuclear cell cultures of patients with severe asthma.

BACKGROUND

Although some studies show that IL-22 and IL-25 play critical roles in the pathogenesis of asthma, little is known about the systemic production of these cytokines. The aim of this study was to assay IL-22 and IL-25 in serum, in mitogen-activated whole blood (WB), and in mitogen-activated peripheral blood mononuclear cell (PBMC) cultures of patients with severe asthma.

METHODS

In this cross-sectional study, a questionnaire was prepared to determine the severity of asthma. Through the questionnaire, information including clinical signs, clinical symptoms, and past medical history were acquired. Information collected allowed all patients who were active or ex-smokers to be excluded. A trained observer assessed airway reversibility, peak flowmetry, and spirometry in the remaining patients. Twenty-one patients and simultaneously, twenty age- and sex-matched healthy controls were selected. Sterile blood (10ml) was taken from each study participant. Sera were isolated and anticoagulant blood used for WB and PBMC cultures and haematological tests. Phytohaemagglutinin and lipopolysaccharide (LPS) were used to activate WB and PBMC. The data from these two groups were compared using Student's t-test.

RESULTS

Although the total white blood cell count was elevated in the asthmatic group, other haematological indices, including IL-22 and IL-25 levels in the asthmatic group were not significantly (p>0.05) different from controls.

CONCLUSIONS

The levels of IL-22 and IL-25 in patients with severe asthma are no higher than those of non-asthmatic individuals. Any major role for IL-22 and IL-25 in severe asthma is likely to be localised to the lungs and bronchial tissues.