Background and Objectives: Acquired aplastic anemia (AA) and paroxysmal nocturnal haemoglobinuria (PNH) are closely related diseases. The objective of our study was to determine the presence of this CD55 and CD 59 deficient clone in patients diagnosed with acquired idiopathic aplastic anemia and to record the clinicohaematological features, treatment and outcome of adults diagnosed with aplastic anemia at a tertiary care institution.

Methodology: All adults diagnosed with aplastic anemia presenting to a tertiary care center in Bangalore over a two-year time period were recruited and followed up. In these patients, the presence of CD55 and CD59 expression on erythrocytes was analyzed using flowcytometery. In addition, the clinicohaemato-logical features; the treatment and response to therapy of these patients were recorded.

Results: Fifty-five patients diagnosed to have idiopathic aplastic anemia (AA) were followed up for a variable time period with a minimum duration of 3-month follow-up. In four of the patients (7.3%), the presence of a small clone of CD55 and CD59 deficient population among erythrocytes was detected at diagnosis. Data from 24 patients who received cyclosporine for at least 3 months were analyzed.. At 3 months 7 out of 24 (29%) showed partial response.At 1 year, out of 9 patients who followed up, 7 patients (77.7%) were in partial remission (PR). Of three patients on androgen monotherapy, 2 patients (66%) achieved partial remission after 12 weeks of monotherapy with danazol and one patient who followed up for 2 years continued to remain in partial remission. The overall response rate (ORR) noted in our study following ATG regime (ATG, cyclosporine, danazol and methylprednisolone) at the end of 6 months was 60%.

Conclusion: Cyclosporine monotherapy was associated with lower response rates as compared to ATG combination therapy. Lower prevalence of CD55 and CD 59 deficient clone was perhaps due to the limitation that flowcytometric analysis was performed on erythrocytes alone.

Keywords: CD 55, CD 59, Aplastic anemia- paroxysmal nocturnal haemoglobinuria.

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Dr Soumya Umesh

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