Clinical significance of antibody specificities to M, N and Lewis blood group system

CONTEXT: The clinically significant antibodies are those active at 37°C and/or by the indirect antiglobulin test. Most of the published literature refers to antibodies of Lewis blood group system to be insignificant, whereas antibodies to M and N blood groups are associated with variable clinical significance. AIMS: The aim of this study is to find the frequency and clinical significance of antibodies to M, N and Lewis blood group systems. SETTINGS AND DESIGN: The study was carried out retrospectively from January 2009 to December 2012. MATERIALS AND METHODS: Antibody screening was performed by solid phase red cell adherence (SPRCA) technique using four cell screening panel on a fully automated platform GALILEO (Immucor Inc. USA). In case of a positive antibody screen, antibody identification was performed using SPRCA (GALILEO, Immucor Inc. USA). RESULTS: A total of 49,077 red cell antibody screens were performed and a total of 427 identifications of red cell antibodies were carried out. A total of 304 specific antibodies were detected: 8.22% of antibodies were of anti-M specificity and 2.96% were of anti-N specificity. Majority (84%) of anti-M and 77.78% of anti-N were of Immunoglobulin G (IgG) class reacting at 37°C. 1.31% of the antibodies were directed against Lewis system antigens of which 0.65% were anti-Lea and 0.65% were anti-Leb. Half of the Lewis system antibodies, i.e., 1 each of anti-Lea and anti-Leb were of IgG class. CONCLUSION: Our study highlights the importance of detecting the thermal amplitude of antibodies with variable clinical significance especially if both IgG and IgM types of antibodies are associated with it so as to establish their clinical significance.