Authors:
A.A. Zachary, D. Kopchaliiska, M.S. Leffell, & J.K. Melancon
Summary:
HLA tetramers are comprised of 4 identical HLA molecules bound to streptavidin and have been used, traditionally, to identify T cells specific for the peptide bound to the HLA molecule. However, we have previously shown that HLA tetramers can be used to quantify HLA-specific B cells and that patients sensitized to the tetramer HLA antigen have significantly higher frequencies of B cells specific for that antigen. We hypothesized that there may be racially determined differences in either the baseline or sensitization-provoked increases in frequencies of HLA-specific B cells that may account for differences in rates of humoral sensitization. We determined the frequencies of B cells specific for HLA-A2, -A24, and -B7 among two groups of blacks and whites: healthy, non-transfused males and sensitized, male renal transplant patients. The table shows the frequencies of tet+ cells among CD19+ cells and number of subjects in each group. We found higher frequencies of HLA-positive B cells among healthy black males which
reached statistical signifi cance for cells specifi c for A2 and A24. The same pattern did not occur among sensitized patients, however, when we examined patients who had received a transplant mismatched for the tetramer antigen, the HLA-specific B cells were appreciably higher among blacks vs. whites for A2 and A24 (the antigens for which there were suffi cient patients to make a meaningful comparison) with the same percentage (210% for A2 and 158%
for A24) increase occurring in both racial groups.
Source:
Congress of the International Transplant Society; 435, Sydney, Australia, 3:30PM-5:00PM (08/11/08)