The study by Loupy et. al. shows an important role for complement-fixing (C1Q+) donor-specific HLA antibodies (DSA) in risk prediction of kidney allograft loss. The study examined 1016 kidney transplant recipients transplanted across negative T- and B-cell cytotoxic crossmatches with subsequent testing by Luminex single antigen beads for the detection of complement-fixing as well as non-complement fixing antibodies. Graft survival was examined and showed that patients who developed C1Q+ DSA had the lowest 5 year graft survival at 54%, compared to patients who developed non-complement fixing DSA (93%), and those who did not develop DSA (94%). In addition, the data also showed that C1Q+ DSA was associated with a greater degree of microvascular inflammation and microvascular damage. This may be an important marker for identifying clinically relevant DSA although questions remain with regards to the kinetics of these antibodies and the association of C1Q positivity with HLA antibodies present at high levels.