The importance of testing for secretor status of ABH antigens: A case series

Abstract

While simple serological tests such as forward and reverse grouping can help identify rare phenotypes, their Confirmation is to be done with a battery of other serological tests including adsorption elution and nonserological tests such as saliva testing for secretor status. Two cases of H-deficient secretor state (para-Bombay) and one case of a weak B phenotype are presented here highlighting the importance of nonserological tests. Case 1: A 50-year-old male who is a repeat blood donor, with no significant history, had “O positive” by forward grouping, “B” by reverse, and no reaction with anti-AB antisera or anti-H lectin. Adsorption elution showed the presence of weak B antigen and saliva testing confirmed secretor status for B and H antigen. Case 2: A 25-year-old primigravida, with no significant history, had “O positive” by forward grouping, “B” by reverse, and no reaction with anti-AB antisera or anti-H lectin. However, adsorption elution showed the absence of any antigen on RBCs. The saliva testing confirmed secretor status for B and H antigen. Both of them were compatible (Coomb's major and minor) with “B” and “O” units and were grouped as para-Bombay B. Para-Bombay phenotypes can present with complete or partial suppression of ABH antigens and nonserological tests are valuable in their diagnosis. Case 3: A 27-year-old first-time blood donor, with no significant history, also had “O Positive” by forward grouping, “B” by reverse grouping, and no reaction with anti-AB antisera. Furthermore, 3+ reaction with anti-H lectin was noted. Saliva testing confirmed secretor status for B and H antigens. He was also compatible with “B” and “O” units and was grouped as “Weak B.” Further classification was not possible as adsorption-elution tests could not be done.