CD44 variant isoforms are specifically expressed on peripheral blood lymphocytes from asthmatic patients

Asthma is a disease characterized by chronic airway inflammation, and Th2 cells play a critical role in initiating and sustaining asthmatic inflammation. It has been shown that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells in the development of airway hyperresponsiveness induced by antigen challenge in the airways. The aim of this study was to determine whether there are specific CD44 variant isoforms (CD44v) expressed on lymphocytes from asthmatic patients. We collected whole blood samples from 103 normal subjects, 165 subjects with asthma and 104 with pneumonia. Peripheral blood lymphocyte isolation was performed, and total RNA was extracted from the isolated lymphocytes, using nested PCR for specific CD44v amplification on lymphocytes. Demographic variables were analyzed using linear regression in order to determine whether the expression of CD44v was correlated with these demographic features. The nested PCR results revealed that CD44v5 was expressed by 55.2% of asthma patients, which was significantly higher than levels of expression in the other groups. Lower percentages of individuals in the normal subject group exhibited expression of CD44v5 and CD44v6. The data demonstrated that the percentage of individuals in the pneumonia group expressing CD44v5 was 29.0%, but a higher percentage of these patients expressed CD44v6. CD44v5 expression was positively correlated with IgE levels (p=0.032) in the asthmatic patient group, and CD44v6 was significantly positively correlated with the neutrophil count (p<0.05). CD44v5 was expressed by a higher proportion of asthmatic patients than other subjects and thus may play an important role in the pathogenesis of asthma. These findings may offer a new target for the diagnosis and treatment of asthma and may also provide insights into the mechanisms of asthma development.