Association between secretor status and respiratory viral illness.

To determine whether non-secretion of blood group antigens is associated with respiratory virus diseases. Study of secretor status in patients with respiratory virus diseases determined by an enzyme linked immunosorbent assay (ELISA) developed to identify Lewis (Le) blood group antigen phenotypes (Le(a) non-secretor; Le(b) secretor). Patients aged 1 month to 90 years in hospital with respiratory virus diseases (584 nasal specimens). Criteria for validation of ELISA (congruence between results on ELISA testing of 1155 saliva samples from a previous study and previously established results on haemagglutination inhibition (HAI) testing, proportions of Le(a), Le(b), and Le- phenotypes in 872 samples of nasal washings from a previous study compared with the normal population). Secretor status of patients determined by ELISA and viruses isolated. Agreement between HAI and ELISA for 1155 saliva samples was 97%. Lewis antigens were detected by ELISA in 854 (97.9%) of nasal washings (Le(a) 233 (26.7%), Le(b) 621 (71.2%), and Le- 18 (2.1%)) in proportions predicted for a northern European population. Secretors were significantly overrepresented among patients from whom influenza viruses A and B (55/64, 86%; p less than 0.025), rhinoviruses (63/72, 88%; p less than 0.01), respiratory syncytial virus (97/109, 89%; p less than 0.0005), and echoviruses (44/44, p less than 0.0005) had been isolated compared with the distribution of secretors in the local population. Secretion of blood group antigens is associated with respiratory virus diseases.