CD4 and cystic fibrosis: To assess whether the percentage of any CD4+ subset was associated with relevant clinical parameters, we analyzed these within the CF group (Table 3), and assessed the correlations of the percentage of each CD4+ subset with continuous variables (age, FEV1% predicted) and any differences between subgroups divided by sex (M = 20, F = 22), genotype (DF508 homozygous = 18, DF508 heterozygous = 21, other = 3).