Volume. 35, No. 2 july. 2011 - The Chest and Heart Association of ...

Study of Direct Antiglobulin Test among the Patients ReceivingFarhana Islam et al.Introduction:Drug induced antibody may coat red cell surfacewhich may cause premature destruction of redblood cells, resulting anaemia. Drug inducedimmune haemolytic anaemia is an acquired formof immune haemolytic anaemia caused by theinteraction of certain medications with patientsimmune system 1 . This interaction induced theproduction of antibodies that damage red cells andresults in premature red cell destruction. Druginduced immune hemolytic anaemia is apart of alarger group of disorders characterized by antibodyproduction against red cells 2 . The red cells maybe coated with antibody, antibody and complement,or complement alone. The mechanism of red celldamage associated with drug induced immunehemolytic anaemia depends largely on whether ornot activate complement typically result inextravascular hemolysis. Those processes thatactivate complement result in red cell lysis andintravascular hemolysis 3 .There are four mechanisms by which drugs arebelieved to induce a positive DAT 1 . Three areimmune mediated. The fourth is a non-immunemechanism that results in the development of apositive DAT, but not associated with hemolysis 1 .The presence of antibody on the red cells does notnecessarily indicate red cell destruction 4 . Manydrugs can cause a positive DAT however, only someof these will cause hemolytic anaemia 1 . As suchthe serologic data must be correlated with thepatient’s clinical history and drug history. Theclinical evidence like fever, anaemia, jaundice thatwould support the diagnosis of drug inducedimmune hemolytic anaemia includes theassociation of hemolysis with the initiation of drugtherapy and resolution with discontinuation of thedrug 3 . The three immune mechanisms are drugadsorption, drug dependents antibody andautoimmune haemolysis 5 .Antibodies that are directed only against the drugbound to the surface of the red cell in characteristicof a drug adsorption reaction. Antibodies directedagainst a combination of the drug and red cellmembrane components are characteristic of a drugdependent or immune complex mechanism.Autoantibody production occurs when the drugstimulates production of antibodies that areprimarily directed against intrinsic red cellmembrane component 6 .Tuberculosis is a disease which needs long termchemotheraphy with multiple drugs having moreor less side effects including hemolysis.Bangladesh is a high burden Tubercular countrywith a ranking of 6 th among 22 high burdencountries of the world 7 . DOTS is the most effectivestrategy available for controlling tuberculosisepidemic. The overall goal of tuberculosis controlis to reduce morbidity, mortality and transmissionof tuberculosis until it is no longer a public healthproblem 6 . For medical treatment of tuberculosis,problem of drug induced hemolysis may causediscontinuation of antitubercular drugs. Rifampicm,isoniazid, streptomycin may cause immunehemolytic anaemia during chemotheraphy oftuberculosis 7 . Rifampicm has been implicated asthe causative drug for immune hemolysis. Theonset of hemolysis was not abrupt and the DATwas strongly positive not only or predominantlyfor Cad, but also for IgG 6,7 . Antitubercular drugscausing immune hemolytic anaemia and positiveDATs include Rifampicin, Isoniazid andStreptomycin 6 . DAT positive antitubercular drugswith immune complex mechanism includeRifampicin, Isoniazid and Streptomycin whichcause intravascular hemolysis. The directantiglobulin test (DAT) also known as the directcoomb’s test demonstrate the presence ofantibodies or compliment on the surface of red cellsand the hallmark of autoimmune hemolysis 9 . Theevidence of hemolysis due to drugs depends ondetection of antibody by direct antiglobulin test(DAT). Other subsidiary evidence include anaemia,hyperbilirubinaemia, hemoglobinuria and renalfailure 6 . Rifampicin dependent antibodies shouldbe suspected in a patient with haemolycis and orrenal failure taking rifampicin. This reaction hasbeen observed in patients taking drugintermittently or irregularly 8 .In this study patients taking antitubercular drugsare included to find the evidence of hemolysis whichmay be due to drug induced antibody by brief clinicalhistory, drug history and by direct antiglobulin test.In this study patients taking antitubercular drugsare included to find the presense of autoantibodyby DAT. A brief clinical history and drug historywith positive DAT is used to diagnose cases of druginduced antibody production.87