A comparison of absorption inhibition and absorption elution methods for estimation of ABO blood groups in saliva

Background: ABO blood groups are the primary, most common, conspicuous, and easily detectable groups. These blood group specific antigens are not the exclusive domain of the erythrocyte, but abundantly present in many other bodily secretions such as sweat, semen and even saliva. Absorption inhibition and absorption elution are the main methods to detect salivary blood group antigens. The aim of this study is to detect the secretor status of 100 samples of saliva and to compare the diagnostic efficacy of absorption elution method and absorption inhibition methods in detecting the ABO (H) blood group antigens in secretors. Materials and Methods: Totally 100 un-stimulated whole saliva samples were analyzed for the presence of ABO (H) blood group specific antigens by absorption inhibition and absorption elution methods. Initially, secretor status was ascertained by detecting the H antigen in saliva, and both methods were used to detect the blood groups from saliva and the results were compared with that of blood which were statistically analyzed. Results: Of the 100 samples, 77 secretors and 23 non-secretors. Using absorption inhibition method 62 out of 77 samples gave results that matched with blood. Using absorption elution 70 out of 77 samples gave matching results. Absorption elution depicted better sensitivity, more true positive matches with blood as well as a higher Kappa coefficient. Conclusion: Absorption elution gave better results than absorption inhibition.