Class-specific antibody response to lymphocytosis promoting factor (LPF) and fimbriae (F) in pertussis.

IgM, IgA and IgG antibodies to lymphocytosis promoting factor and fimbriae were measured by enzyme-linked immunoassay in seropositive and/or culture-positive patients without symptoms of pertussis, culture-negative patients with typical whooping cough symptoms, and culture-positive patients with typical symptoms. The culture-negative patients with typical symptoms had higher antibody levels in the first specimens and stronger responses to these antigens than the other patients. Antibody levels in the first specimens and antibody responses did not correlate with patients' age and duration of symptoms before taking of the first specimens. Thus, no correlation occurred between the symptoms of pertussis and antibody levels or antibody responses to fimbriae or lymphocytosis promoting factor. Bacteria were less likely to be isolated from those with strong antibody responses and this stresses the need of using both isolation and serology in the diagnosis of pertussis.