Abundance of leukocytes in a tissue can predict a patient's risk for receiving an infection from donor tissue. Independent publication uses PBMCs from HemaCare as positive control in an assay to easily predict allograft success.
Organ transplantation is a huge undertaking with the transplant team betting on a high probability of success. One caveat to success is the transmission of an infectious disease from donor to recipient. The transmission of infection by organ donor can catastrophically result not only in loss of the allograft but also in death of the immunosuppressed patient. It is therefore essential to determine if the potential donor has an infection that could be transmitted to the recipient.
Globally, the requirements for infectious disease screening of donor samples varies. Take the example of the cancer-causing Human T-Lymphotropic Virus, HTLV; in North America, establishments including HemaCare, routinely test tissue and PBMC donors for antibodies to HTLV. However, in European countries such as Germany, such screening is not mandatory nor frequently performed.
Rather than testing for each specific viruses which is timely and costly, one solution would be to test for the presence and concentration of the passenger vehicle that transports viral diseases, such as peripheral blood mononuclear cells (PBMCs), which include lymphocytes. HTLV integrates into lymphocytes, and therefore screening to identify tissues that are leukocyte depleted would eliminate the need for direct HTLV testing.
Investigators have reported that the presence of a threshold number (minimum number) of contaminated viable lymphocytes is required for seroconversion (detection of antibodies) to HTLV to occur – highlighting the importance of screening for the dose of PBMCs carried through to organ transplant recipients.
Furthermore, investigators have highlighted cases of delayed seroconversion despite the positive presence of viral DNA, which emphasizes uncertainty in the relevance of antibody testing. This further supports the importance of testing for PBMC load in donor organs.
Dr. Russell Marians and his team recently reported a quantitative polymerase chain reaction (qPCR) assay for quantifying leukocytes in donor tissue. They used the gene for CD45 as a biomarker for leukocytes to indicate the number of lymphocytes present in the PBMCs.
Assay design included leukocytes from remnant leukapheresis units, amniograft, corneas, and fresh skin grafts. Dr. Marian’s group used PBMCs supplied by HemaCare derived by leukapheresis, as positive control. qPCR was run on all samples and demonstrated that the qPCR assay was consistent with the relative abundance of leukocytes predicted for each tissue.
Through this proof of concept study, they demonstrated the utility of their method for screening the relative abundance of PBMCs in donor tissue. The ease of this simple assay could improve allograft success while streamlining screening for infectious agents in donor tissue.
Read more about their findings and access the full publication.
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- Cari E. et al., A Quantitative Polymerase Chain Reaction Test to Enumerate Leukocytes in Allograft Tissue and the Implications for Donor Eligibility Testing.
Cells Tissues Organs 2013;198:221–226. doi: 10.1159/000355138.
- Glowacka, I. et al., Delayed Seroconversion and Rapid Onset of Lymphoproliferative Disease After Transmission of Human T-Cell Lymphotropic Virus Type 1 From a Multiorgan Donor. Clinical infectious diseases 2013 Nov;57(10):1417-24. doi: 10.1093/cid/cit545.