Pharmacological Control of Eosinophil Activation and Secretion

Human eosinophils may be prepared from blood taken from normal, atopic, asthmatic, or hypereosinophilic donors. Eosinophils are purified from buffy coat cells on metrizamide or Percoll density gradients. The interaction between platelet-activating factor (PAF) and eosinophils may be of relevance in allergic diseases, PAF may be one of the mediators that play a role in selective accumulation of eosinophils in the airways and may be involved in their activation. PAF is potently chemotactic for human eosinophils in vitro and has a greater effect on eosinophils than neutrophils. G-Proteins are involved in coupling surface receptors to second messenger systems. G-proteins are also involved in eosinophil degranulation and a novel G-protein associated with exocytosis. Corticosteroids are the most effective anti-inflammatory drugs used in the treatment of asthma and they reduce airway hyper-responsiveness. Corticosteroids reduce the numbers of circulating eosinophils and inhaled steroids reduce the number of hypodense eosinophils in the circulation of asthmatics.