RESUMO
Background & objectives: Swiss-type hereditary persistence of foetal haemoglobin (HPFH) has been shown to be responsible for the wide range of F cell levels in healthy Thai adults. However, a survey for F cells in healthy Thai adults has not been performed. This study was conducted to determine the F cell distribution in adult Thai blood donors and to assess the possible involvement of ?-thalassaemia and haemoglobin E (HbE) carriers in increased HbF levels. Methods: Thai blood donors (n=375, 205 males and 170 females) were included in the study. Blood samples were collected for measuring haemoglobin (Hb) concentration and haematocrit (Hct) and F cell levels. Hb and Hct levels were determined by automated blood counter, while F cells were quantified by flow cytometric analysis of F cells stained by fluorescein isothiocyanate-conjugated anti ?-globin monoclonal antibody. Finally, F cell levels were compared between blood samples having mean corpuscular volume (MCV ) <80 fl and ?80 fl as well as between ?-haemoglobinopathies (HbE and ?-thalassaemia carriers) and normal adults. Results: F cell levels varied markedly spanning 0.80-39.2 per cent with a positively skewed distribution. Thirty two per cent of these individuals had F cell levels more than the 4.5 per cent cut-off point. F cell levels in females were significantly higher than those in males (P<0.05). F cell levels in individuals having MCV <80 fl were significantly higher than those having MCV ?80 fl (P<0.05). ?-haemoglobinopathy (HbE and ?-thalassaemia carriers) had significantly higher F cell levels than normal individuals (P<0.05). Interpretation & conclusions: The present results showed that besides Swiss-type HPFH, the ?-haemoglobinopathy was expected to be involved in increased F cell levels in adult Thais. Thus, influence of ?-haemoglobinopathy must be considered in interpreting F cell levels in area endemic of this globin disorder.