Chlamydia pneumoniae and possible relationship to asthma. Serum immunoglobulins and histamine release in patients and controls.

Chlamydia pneumoniae (C.pn.) is claimed to be of importance for the development of bronchial asthma in previously healthy individuals. This is a new and speculative theory. Earlier studies have mainly focused on C.pn. and exacerbation of asthma. If this new theory were true, one would expect titres of C.pn.-specific IgG to be higher or more common in patients compared with controls. It would also seem probable that pathobiological mechanisms as found in connection with other microorganisms could be demonstrated, i.e. presence of C.pn.-specific IgE and the capability of C.pn. to induce or enhance histamine release from basophil leukocytes. We therefore examined C.pn.-specific IgE, IgG and IgM in sera from 22 adults with bronchial asthma and 25 healthy controls. IgE was verified by passive sensitization of basophils from umbilical cord blood. The prevalence of IgE was approx. 69% and IgG approx. 23% in both groups. IgG-titres were between 1:16 and 1:64 in both groups. No IgM was found. Further, C.pn. could neither induce nor enhance histamine release from basophil leukocytes of patients or controls. We conclude that patients with bronchial asthma and healthy controls do not differ in relation to 1) C.pn.-specific IgE in sera, 2) the capability of C.pn. to induce or enhance histamine release from basophil leukocytes, since no such effect was found, or 3) previous C.pn. infection judged by the presence of specific IgG antibodies. Our results cannot support the theory that C.pn. is a cause of adult-onset asthma.