Lymphocyte markers and disease activity in asthma

Though symptoms may be episodical, the bronchial inflammation underlying bronchial asthma is nowadays appreciated to be of a chronic nature. This ongoing inflammatory process is likely to depend at least partially on the local and systemic activation of mononuclear cells. Accumulation of T-lymphocytes in the airways of patients with asthma has been reported both from post mortem as from bronchial lavage and biopsy studies. The lymphocytes attracted to the lungs appear to be activated, with respect to increased expression of HLA-DR and CD25 antigen, when compared with non-asthmatics. Although T-cell attraction and activation in the (peri-)bronchial compartment is most evident in asthma, signs of activation of T cells in the peripheral blood can also be measured. Both IL-2R (CD25) expression HLA-DR expression and expression of CD23 antigen were found to be elevated. Further increases in activation of peripheral blood mononuclear cells were found during asthmatic attacks. Corrigan et al. measured surface expression of various T cell membrane proteins in 14 asthmatic patients who were admitted to the hospital with symptoms of acute severe asthma. In comparison with normal controls an increased expression of IL-2R and HLA-DR was observed at admission, which were less raised at day 7. The increase in IL-2R expression was limited to the CD4 super(+) T cell subset. The problem with measuring immunological parameters as cell activation during asthmatic attacks is that the observations may partly or largely be due to the precipitating event of the attack, e.g. viral infections, rather than a feature of the asthmatic process itself. Furthermore, asthma is a multifactorial disease in which the pathogenetic processes differ from patient to patient.