[Study of IGG subgroups as prognosis markers in cystic fibrosis].

Pressler et al. (1988) showed a correlation between elevated serum levels of IgG2 and IgG3 with decreased lung function. We tried to verify that hypothesis and to evaluate the usefulness of IgG subclasses as prognostic markers in 54 cystic fibrosis patients. The serum levels of the IgG subclasses were determined by radial immunodiffusion and correlated to Vital capacity (VC), obtained with a bell spirometer (Biomedin), and to oxyhemoglobin saturation (SaO2), obtained with a pulse oximeter (Minolta Pulsox 7). For statistical analysis, Student's "t" test, Pearson's chi-square and multiple regression were used. Significance was accepted at p < 0.05. We found significant correlation between elevated serum levels of IgG1 and decreased VC (r = -0.53; p < 0.01), and between high levels of IgG1 and decreased SaO2 (r = -0.45; p < 0.01). Elevated serum levels of IgG1 are significantly correlated with high levels of IgG2 (r = 0.41; p < 0.05) and with high levels of IgG4 (r = 0.43; p < 0.05). There is significant correlation between the increase in IgG4 and SaO2 impairment (r = 0.51; p < 0.01), but no significant correlation between IgG4 and VC was found. Patients with elevated serum levels of IgG1 had significantly lower VC than patients with IgG1 below the normal range (p < 0.002). No difference in VC was found, when comparing patients with low and high levels of the other subclasses.(ABSTRACT TRUNCATED AT 250 WORDS)