Abstract
INTRODUCTION: Cord blood units (CBU) are tested at banking for markers relevant to donor safety (infectious disease markers) and hematopoietic stem cell transplantation (cellularity and HLA typing). As CBUs are being increasingly used for new, non-transplant purposes, additional markers are sometimes needed for CBU selection. OBJECTIVE: We describe here our procedure for testing CBU, looking for specific NK cell characteristics: KIR haplotype B (associated with more activating KIRs), and Fc gamma receptor III A (FCGR3A) 158 V/V (presence of a homozygous valine in position 158) polymorphism (which has a higher affinity for IgG), as requested by some of our clients for non-transplant studies. METHODS: First, a list of eligible CBUs was established, based on the order specifications. Testing was requested from an outside lab (Histogenetics, Ossining, New York). As CBU DNA is a precious resource, we wanted to limit the number of new samples to be sent by first testing leftover samples from HLA typing, then sending additional samples to the lab, to reach the required number of CBUs. Testing was done sequentially (Figure 1): first, KIR typing, then FCGR3A polymorphism on the CBU with KIR B haplotype. RESULTS: A total of 216 samples were selected for KIR testing (130 from stored DNA and 86 from newly sent DNA); 154 (71%) were found to have at least one B haplotype receptor. For those, FCGR3A polymorphism was tested; 60 samples (39%) were F/F, 70 (46%) F/V, and 23 (15%) V/V (Figure 1), in line with expected frequencies from the literature. Average TAT for KIR testing was 13 days and an additional 18 days for FCGRA3. DISCUSSION: Performing additional testing can easily be integrated into a bank’s routine and help select CBU for purposes other than transplantation. When several markers are needed, sequential testing is an efficient and cost-saving method.