Cyclosporin A, apoptosis of BAL T-cells and expression of Bcl-2 inasthmatics

The late asthmatic reaction is characterised by elevated numbers of interleukin‐4/interleukin‐5/CD4‐positive T‐helper cells type 2 in bronchoalveolar lavage fluid (BALF). Cyclosporin A (CsA) is known to inhibit T‐cell proliferation, induce apoptosis of CD4‐positive T‐cells and downregulate cytokine gene expression. It was assessed whether CsA‐induced inhibition of the late asthmatic reaction was associated with apoptosis of BALF T‐lymphocytes and other cell types, as well as expression of the antiapoptotic protein B‐cell leukaemia/lymphoma 2 gene product (Bcl‐2). BALF cells were obtained from asthmatics at baseline and 24 h after allergen-inhalation challenge following prior administration of CsA (n=13) or placebo (n=11). The number of apoptotic CD3‐positive T‐lymphocytes increased in the CsA but not the placebo group. The numbers of Bcl‐2‐positive cells were significantly reduced in the CsA but not the placebo group. The majority of Bcl‐2‐positive cells were CD3‐positive T‐lymphocytes. The beneficial effect of cyclosporin A in asthma may be related to its inhibitory effect on the late asthmatic reaction via induction of T‐cell apoptosis and decreased B‐cell leukaemia/lymphoma 2 gene product levels.