Detection of antibodies to HLA-DP in renal transplant recipients using single antigen beads.

With the development of single DP-antigen beads, antibodies to DP could clearly be segregated from other HLA antibodies. We studied 323 sera of patients from four different centers with functioning or rejected kidney grafts. DP antibodies were found in 5.1% of 138 patients with functioning grafts, and 19.5 % of 185 patients with rejected grafts (P<0.001)). 42.9% and 63.9% of the DP antibody positive patients had DR/DQ antibodies among the functioning and rejected group. Among patients who did not have Class I and DR/DQ antibodies, 13% of those who rejected a graft had DP antibodies, compared to 3.5% of patients with functioning grafts (P<0.05). DP 0301 had the highest specificity frequency in the rejected group. In conclusion, HLA-DP antibodies were detected at a higher frequency in patients who have rejected their grafts than those with functioning grafts. For regrafts, DP tissue typing is recommended to avoid presensitized DP alleles.