T lymphocyte subset profile and serum alpha‐1‐antitrypsin in pathogenesis of chronic obstructive pulmonary disease

Summary Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by the presence of non‐fully reversible airflow limitation. The study was undertaken to investigate the involvement of alpha‐1‐antitrypsin (α 1 AT) and T lymphocyte subsets in the pathogenesis of COPD. Blood samples of 50 subjects, including 25 healthy volunteers and 25 patients with COPD, were analysed. Serum trypsin inhibitory capacity (STIC) was determined by enzymatic assay. CD4 +  and CD8 +  T lymphocytes were enumerated in heparinized blood using a fluorescence activated cell sorter counter. The STIC in COPD patients was found to be decreased significantly than in controls ( P  < 0·01). In COPD patients with lower expression levels of α 1 AT, a highly significant decrease in the number of CD4 +  T lymphocytes ( P  < 0·0009) and CD4/CD8 ratio was observed compared with control subjects ( P  < 0·008). The mean ± standard error of CD8 + lymphocytes was found to be little different (only marginally decreased) in COPD patients compared to healthy controls; however, an alteration in the individual count of CD8 + lymphocytes cells was observed in COPD patients. Using linear regression analysis, a negative correlation was observed between STIC and CD4 + lymphocytes and CD8 + lymphocytes ( r  = −0·40, P  < 0·04; r  = −0·42, P  < 0·03, respectively) in COPD patients. An alteration in α 1 AT and T lymphocyte subsets in COPD patients suggested that interplay of these factors may be responsible for the progression of COPD.