Association between rise in antibodies and increase in airway sensitivity after intramuscular injection of killed influenza virus in asthmatic patients.

Nineteen stable asthmatic patients were given killed influenza virus intramuscularly. In 9 patients who developed a fourfold or greater rise in haemagglutination antibodies, an increase in airway sensitivity to histamine was demonstrated 48 h later. There was no significant change in histamine sensitivity in those patients who failed to develop a fourfold rise in haemagglutination antibodies. The increased histamine sensitivity was not associated with a deterioration in asthma symptoms, peak expiratory flow, nor an increase in bronchodilator requirements.