Detection of cytomegalovirus antibody in platelet concentrates by fluorescence immunoassay and latex agglutination

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Abstract
A passive latex agglutination (PLA) test for cytomegalovirus (CMV) antibody detection has been shown to be an acceptable method of screening both donor sera and plasma from units of red cells and platelets stored in CPDA‐1. However, most plateletpheresis concentrates are collected in ACD, and CMV antibody testing of ACD‐stored products has not been systematically evaluated by PLA. Sera and ACD‐stored platelet concentrate bag segments from 104 donors were tested by PLA and by a solid‐phase fluorescence immunoassay (FIAX) as a reference standard for CMV‐IgM and CMV‐IgG antibodies. Sera were stored at both 4 and 22 degrees C and were tested on Days 1 and 5 of storage; segments were tested daily for 5 days. Of 63 donor samples (61%) that tested negative for CMV‐IgG by FIAX, there were two false‐positive results in bag segments by PLA testing, one on Day 1 and the other on Day 2 of storage. PLA testing was consistently positive in sera and segments in the 40 donors (38%) who tested positive for CMV‐IgG by FIAX. Potential false‐negative PLA results occurred in five bag segments derived from one donor whose serum gave equivocal CMV‐IgG results on FIAX. The sensitivity and specificity of the PLA assay were 100 percent for donor sera tested at both 4 and 22 degrees C and 91.5 and 98.4 percent, respectively, for platelet bag segment tests. Although no donors positive for CMV‐IgM were identified, 15 (14.4%) had equivocal IgM anti‐ CMV test results. The PLA ositivity of these samples correlated solely with the presence or absence of lgG as detected by FIAX. A total of 648 PLA tests were performed on donor sera and on platelet bag segments. On1 two false‐positive and five false‐negative results were observed. PLA testing for CMb antibody in donor sera and in ACPstored platelet concentrates is accurate and sensitive for up to 5 days. Segments may be remed from platelet bags for testing throughout the May shelf life of plateletpheresis components and Will Still provide accurate CMV testing result.