Anti-pneumococcal antibodies (anti-PS): lack of standardisation between assays skews UK national external quality assessment services (UKNEQAS) consensus targets

Introduction: Anti-PS assays are used to assess immunodeficiency. Our in-house ELISA is calibrated against the FDA 89SF standard. Assay standards and samples are pre-adsorbed with capsular polysaccharide (CPS) and 22F. The UKNEQAS programme is dominated by the Binding Site VaccZyme anti-PCP (>90% participants). This ELISA uses a purified protein standard pre-adsorbed with CPS only.