A report of an anti-H antibody with a wide thermal range in a group A(1) blood donor.

Over the last few decades immunohaematology laboratories have developed ever more sensitive methods for typing red blood cells and detecting irregular antibodies. The introduction of solid phase technology1,2 in the mid 1980s, and of column agglutination technology (CAT)3,4 at the beginning of the 1990s, as well as the use of new and alternative potentiating media (polyethylene glycol, PEG)5 and more sensitive panels with red blood cells suspended at 0.8% in potentiating solutions (B-LISS), have improved the ability of tests to identify weak antibodies, otherwise not readily detected by traditional tests in the liquid phase in test-tubes. It is, therefore, possible that in routine daily practice, samples can give positive results for irregular antibodies detectable only when the serum is tested with CAT or in solid phase antibody screens. The interpretation of these cases is, however, often difficult and a definitive identification is not always achieved, particularly when the antibodies react with all the red cells in the panels.Although such immunohaematological situations may, sometimes, be caused by weak, cold antibodies of no clinical relevance, in other cases they can be caused by high titre, low avidity (HTLA) antibodies, or very weak low titre antibodies, which, ideally, should be identified in order to enable correct management of transfusions or to monitor foetal risk during a pregnancy. The case we report here concerns an unusual pan-agglutinating IgG antibody with anti-H specificity in the serum of a young blood donor, who had never received transfusions.