Frequency of HLA DR2 in patients with severe and very severe aplastic anaemia

Abstract

Objective: To determine the frequency of HLA DR2 in Pakistani patients with severe and very severe aplastic anaemia. Introduction: In many cases aplastic anaemia is mediated by the immune mechanisms. Increased frequency of certain HLA haplotypes in patients with autoimmune diseases have led to the investigation of HLA subtypes in aplastic anaemia. HLA DR2 was found to be the most frequently encountered allele in aplastic anaemia. It has been reported that patients of aplastic anaemia, who possess HLA DR2 show a good response to immunosuppressive treatment. This study has been designed to establish frequency of HLA DR2 in patients of aplastic anaemia in our population. Setting: Armed Forces Institute of Pathology and Armed Forces Bone Marrow Transplant Centre, Rawalpindi-Pakistan. Materials and Methods: Fifty two cases of aplastic anaemia diagnosed at AFIP/AFBMTC during last 03 years (March 2001 to December 2003) were included in the study. Laboratory investigations to establish the diagnosis included blood complete picture, reticulocyte count, bone marrow aspiration and bone marrow trephine biopsy. Cytogenetic studies were carried out in selected cases to exclude possibility of hypoplastic myelodysplastic syndrome/Fanconi`s anaemia. LAP score, ham`s test, sucrose lysis test, urine for haemosiderin and CD59 analysis were carried out in suspected cases to exclude paroxysmal nocturnal haemoglobinuria. All cases were tested for HLA DR2 by standard National Institute of Health two stage microlymphocytotoxicity assay. Results: Out of 52 patients, 35 were males and 17 were females (M: F 2:1). Median age of the patients was 17 years (3-35 years). Twenty eight (54%) of the patients were of severe aplastic anaemia and 24 (46%) were of very severe aplastic anaemia. HLA DR2 was positive in 31(60%) patients compared to 4,1% in healthy population (p. 0.007). Conclusion: An increased frequency of HLA DR2 is also seen in Pakistani patients of aplastic anaemia which is associated with a good response to immunosuppressive therapy.