Lymphocyte subpopulations and function in cystic fibrosis.

Circulating lymphocytes subpopulations and their function have been studied in 25 young adults with cystic fibrosis (CF) and 25 normal controls. Mean absolute numbers of all lymphocyte subsets in the CF group were not significantly different from the controls. Antibody-dependent cell cytotoxicity was significantly higher in the CF patients who had Pseudomonas aeruginosa in their sputum compared with those who had not and compared with the normal controls. Within the CF group the numbers of B cells, total T cells and OKT4+ helper cells fell as percent predicted peak expiratory flow (PEF) declined and similar significant positive correlations were found between lymphocyte subsets and percent predicted body weight. Serum albumin levels also showed a positive correlation with total T lymphocyte numbers (p less than 0.05). In vitro lymphocyte proliferative responses to mitogen were not significantly different from the control group, but again correlated positively with body weight in the CF patients. This provides further evidence that immune function in CF patients may become impaired as pulmonary disease and nutritional status deteriorate.