Abstract: Objective To explore whether the AB plasma dilution method can replace the saline method for alloantibody titer detection, or which method also can eliminate the influence of high titer autoantibodies, or detecting alloantibodies. Method Four groups of specimens were prepared for testing: ①six samples with autoantibody; ②sixteen samples with known alloantibody; ③16 mixed samples using ①and ② (artificially mixed 6 autoantibody plasma and 16 known alloantibody plasma according to certain rules); ④ Four samples with autoantibodies which contain anti -C, anti -E, anti -Jka, and anti -CE alloantibodies, respectively. We serially diluted the samples of groups ①, ②, and ③ with saline or AB plasma, respectively and measured their titers using AHG test (microcolumn method). Diluted the samples of group ④ with AB plasma, and screened for irregular antibodies. Result ①6 autoantibody samples in group were diluted with saline at titers of≥512, where as with AB plasma the titers of≤4;② only one pair of anti-M titer of 2 was inconsistent, which was 2 using the saline dilution method, and was 4 using the AB plasma dilution method. When the titers were ≥ 4, the both results were consistent; ③ When their original titers≥ 16, there was no difference between the saline and AB plasma dilution method. When those titers<16, titers with saline dilution method keep 16. When the original titer of alloantibody ≥ 8, the AB plasma dilution method can detect the same titers as the original same antibody. When the titer is ≤ 4, it cannot distinguish between the alloantibody and the autoantibody. ④In the AB plasma dilution test, there was a change in the pattern of antibody screening reaction in a 1∶8 test tube for four recipients with autoantibodies, which pattern corresponding with anti -C, anti- E, anti -Jka, and anti -CE antibodies respectively. Conclusion Extremely high titer autoantibodies are detected with the saline dilution method , where as the AB plasma dilution method can eliminate the influence of 1∶4 titer autoantibodies in test tubes; AB plasma as a dilution solution does not affect the titer detection of alloantibodies, which is slightly better than the saline dilution method; AB plasma dilution, in the presence of highly effective autoantibodies, can detect the presence of alloantibodies with a titer ≥ 8 based on different changes in the screening pattern of the three line antibodies. It is a relatively simple immunohematological experimental method that can avoid interference from autoantibodies.

Key words: Autoantibodies, AB plasma, Dilution, AHG test (microcolumn method)