DefinePK

Abstract

Blood groups are inherited in accordance with the principle of Mandel1 and they remain unchanged throughout the life2. Change in blood group antigen or antibody content may occur in cases of malignancy so that grouping of such patients occasionally present some problems. Sometimes there is a lack of the autoantibodies (Anti A and/or Anti B) because the patient has little or no gamma globulin in his serum. Oc­casionally more antibody is formed, e.g. anti-B has been found in A, B. Sometimes an excess of blood group substances occur in the serum which may lead to the neutralisation of the anti A and B grouping sera, unless the patient’s red cell are carefully washed several times. Also it is common to find antibodies especially in case of leukaemia3. The commonest change in red cell is that they become poly agglutinable due to the exposure of the T antigen on the cell antiT occurring in all adult human sera. Other changes which may occur are reduction in strength of the A agglutinogen, the acquisition of pseudo B antigen by a cell and alternation in strength of the Rh — antigen4. It is also possible to find antibodies specific for D antigen in person whose red cells are D positive. Such antibodies are negative with a very few D positive person including the individuals in whom the antibodies are formed. Itis suggested the D antigen is a complex one and these antibodies are specific for different part of it. It is, when a part of D antigen is missing in a particular individual that a antibody to the missing fraction may be formed. So far four different fractions with cor­responding antibodies have been found RhA, Rh and RhD. Most D positive individuals possess all the fractions so they do not form the antibodies5.