FIGURE 1.

Low plasma levels of anti‐αGal antibody in humans with increased burden of lower airway infections. Anti‐αGal antibody was quantified in plasma samples by solid‐phase immunoassay. (A) Comparison of anti‐αGal levels in healthy persons (control, n = 60) and in patients suffering from recurrent infections (n = 289) to a degree prompting experienced medical specialist to suspect causative primary immunodeficiency. Patients were categorized according to their dominating site of infection: (i) non‐airways (n = 118), (ii) upper airways (n = 53) and (iii) lower airways (n = 118). The black bars show the geometric means with 95% confidence intervals. The control group was compared with each of the patient subgroups based on bootstrap sampling distributions (Figure S2), and significant group difference (P < 0·05) in the anti‐αGal levels is marked by a grey horizontal line and asterisk. (B) As in panel A but for patients with idiopathic lower‐airway infections (from panel A) compared with an additional control group comprised of patients with severe lung damage (lung transplantation candidates) and thus highly increased tendency to acquire lower‐airway infections (n = 34)