Influenza Virus Neutralizing Antibody in Human Respiratory Secretions

Abstract

Influenza virus neutralizing antibody titers and immunoglobulin levels were measured in human respiratory secretions. Antibody in the IgA class of immunoglobulins was found in respiratory secretions obtained during life, whereas IgG antibody predominated in secretions obtained at autopsy. The amount of neutralizing antibody per milligram of IgA was found to be similar in sputum and nasal washing, but was significantly lower in saliva. There was a positive association between levels of serum antibody and sputum and nasal washing antibody. The antibody in respiratory secretions formed in response to a strain of A2 influenza virus had similar neutralizing activity against a different but closely related A2 influenza virus strain.