Comparison of three methods of cross-matching to detect canine DEA 7 blood incompatibility

trifuged and plasma samples were cross-matched against two samples of DEA 7-positive and three DEA 7-negative RBCs using the GEL technique. Samples that showed >1+ agglutination strength with DEA 7–positive RBCs samples but not with DEA 7–negative RBCs samples were classified as containing naturally occurring anti–DEA 7 antibodies. Samples that showed no agglutination with DEA 7-positive RBCs were classified as containing no anti-DEA 7 antibodies. Thirdly, the 40 DEA 7-negative plasma samples were cross-matched in double blind fashion with the two DEA-7 positive RBCs samples using TUBE and immunochromatographic kit and results were compared with those of the agglutination on GEL, considered the gold standard technique. A positive/incompatible cross match was identified when agglutination, hemolysis, or both reactions were present with TUBE technique or when a red band, other than the control one, was identified on the immunochromatographic strip. To determine relationship between results obtained with various methods, 2 x 2 tables were used. Cohen’s kappa coefficient (K) was calculated with 95% confidence interval (95%CI) between results of GEL and other methods. With GEL agglutination 21/40 plasma samples showed positive cross-matching and 19/40 showed negative cross- matching. The same results were obtained by TUBE cross match, whilst only 1/40 sample showed positive cross matching with immunochromatography. There was a statistically significant relationship between results of GEL and TUBE methods (P<0.000), but not between GEL and immunochromatography results (P=1,000). Agreement quantified by kappa showed perfect (K=1,000, 95% CI 1,000 to 1,000) agreement for comparison of TUBE to GEL, but agreement equivalent to chance (K=0,0453; 95% CI -0.0427 to 0.133) was seen between GEL and immunochromatography. GEL column and TUBE crossmatch tests are useful methods to evaluate DEA 7 blood compatibility, whereas the immunochromatography was not able to identify DEA 7 incompatibilities due to anti-DEA 7 naturally occurring antibodies.