The Immunohematology Manager at the Community Blood Center of Kansas City, Missouri (attribution used with permission) asks the following question (verbatim):

"I would like to if ask any laboratories currently using GTI PakPlus® or Pak®12G are utilizing GTI's "no antigen wells (NAW)" [www.gtidiagnostics.com], and if so, have they developed an in-house algorithm for their use? Our laboratory has forwarded several patient samples with weak reactivity with all, or most wells in Pak® 12G and/or PakPlus® to GTI for resolution. These samples were nonreactive with both Immucor assays (Capture-P® and Capture-P® Ready Screen, www.immucor.com). While we realize that no one assay will detect all antibodies, we had no way to report meaningful results to clinicians from the GTI results. We requested GTI confirm or refute the presence of platelet antibody (auto or allo) in these specimens. In addition to repeating our testing and running MACE assays (Modified Antigen Capture Enzyme linked immunosorbent assay) on the specimens, GTI tested the specimens with their NAW. They reported no platelet antibody by MACE, confirmed our nonspecific reactivity in the PAK® assay and reported reactivity with NAW, indicating nonspecific (false positive) reactivity in the assay. They further suggested we order NAW to help resolve similar problems in the future. Despite repeated requests, the manufacturer will not provide any information on the use of NAW (i.e., what OD value with the NAW would invalidate the patient's results, or NAW to test value ratio that would indicate nonspecific reactivity). We are collecting data in an attempt to develop an in-house algorithm, but would relish input from other labs using this assay."

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator