Acute asthma compared with exacerbations of chronic bronchitis: changes in complement.

Complement levels were measured on admission and at 1 and 7 days following admission in twenty patients with acute severe asthma and ten patients with an acute exacerbation of chronic bronchitis. Although no evidence of hypocomplementaemia was found in any patient, there was a mean fall within the normal range of the individual complement components, C4, C3 and factor B in both groups. The mean fall occurred earlier in the bronchitics than in the asthmatics and this may be related to infection or the administration of corticosteroids. There was a significant fall in C3 (P greater than 0.05) in the bronchitics compared with the asthmatics at 24 hr. From our study, however, we could find no evidence of excessive utilization of complement in acute asthma.