Exercise induced mobilisation of the marginated granulocyte pool in the investigation of ethnic neutropenia

This study was designed to determine whether ethnic neutropenia is caused b y an increased proportion of neutrophils being present in the marginated gr anulocyte pool. Thirty two healthy volunteers, half of whom were African or Afro-Caribbean and half of whom were white, exercised vigorously for 10 mi nutes on a step machine to mobilise granulocytes from the marginated granul ocyte pool into the circulating granulocyte pool. The amount of work perfor med and the pulse rate response of the two ethnic groups were compared to d etermine whether the exercise carried out was comparable. A full blood coun t and an automated differential count were performed before and after the e xercise. The haemoglobin concentration, platelet count, and absolute counts of total leucocytes and leucocyte subsets before and after exercise were c ompared in each individual and the values in the two ethnic groups both bef ore and after exercise were compared. The absolute increase in neutrophils in the two ethnic groups was compared. The African/Afro-Caribbean group was found to have a reduced rather than enhanced ability to mobilise neutrophi ls from the marginated granulocyte pool. Therefore, increased margination o f neutrophils is unlikely to be the cause of ethnic neutropenia.