CD79A and chronic rhinosinusitis with nasal polyps: With regards to S-IgA levels in nasal secretions, results are a bit less straightforward; while a large study performed by Tsybikov et al. (114) found increased S-IgA levels in 54 patients with CRSwNP compared to 40 healthy controls, this increase was not in keeping with the—smaller—study by Hupin et al. (15).