Eosinophil activity reflects clinical status in patients with asthma before and during a prednisolone course

Both overtreating and undertreating asthma can be harmful, either because of side effects or development of uncontrolled asthma. As the eosinophil granulocyte is of importance in asthma, it is logical to study this cell in the search for a marker for the right level of treatment.

To study the changes in eosinophil activity and the correlation to clinical status in asthmatic patients who have deteriorated and during prednisolone treatment.

Nine patients were studied on two occasions: with exacerbation (visit 1) and during prednisolone treatment (visit 2). Clinical evaluation was performed as well as analysis of percentage of eosinophils, eosinophilic cationic protein (S-ECP) in serum and expression of intracellular ECP, measured by cell flow cytometry using a monoclonal antibody (EG2) against the activated form of ECP.

Visit 1: four patients had eosinophils above normal, mean 6.5%, range 1.5 to 13.8. S-ECP was measured in seven patients of whom five had values above normal (16 micrograms/L), mean 29.5, range 1.5 to 13.8. Intracellular expression of ECP was above normal (mean 26.7 +/- 10.8) in seven out of nine (mean 48.1, range 28.8 to 69.6). Visit 2: all patients improved and all eosinophil parameters decreased. The eosinophil concentration fell to a mean of 3.0%, range 1.0 to 6.6, S-ECP to a mean of 10.5 micrograms/L, range 3.2 to 17 and intracellular expression of ECP to a mean of 33.4, range 19.4 to 40.9.

Reduction in eosinophil activity followed improvement in clinical condition. Measuring intracellular expression of ECP may be of value in addition to eosinophil count and S-ECP in monitoring asthma.