37.3.3. Freelite and Hevylite antigen excess detection on the SPAPLUS
Freelite and Hevylite IgMκ and IgMλ SPAPLUS assays include antigen excess parameters (Sections 7.5 and 11.4), and are based on reaction kinetics monitoring, using the same method as the Optilite (Section 37.2.3). Samples detected as being in antigen excess are automatically flagged by the instrument with a prozone (P) flag and the sample is automatically re-assayed at the higher re-dilution. Cha et al. observed that the SPAPLUS algorithm for antigen excess detection correctly identified samples in antigen excess.