Humoral Immune Response of Humans to Lipooligosaccharide and Outer Membrane Proteins of Haemophilus ducreyi

Abstract

The humoral immune response to purified lipooligosaccharide (LOS) and outer membrane proteins (OMP) of Haemophilus ducreyi was evaluated. Sera from chancroid-endemic (Uganda, Kenya) and -nonendemic (Canada) countries were tested by an ELISA. The response to OMPs was cross-reactive with other Haemophilus species, and elevated levels of antibody were detected in patients that did not have chancroid. The LOS component stimulated an H. ducreyi-specific immune response that was detected only in patients with chancroid. The sensitivity of the LOS ELISA was 96% (95% confidence interval, 89.9%-100%) and the specificity was 97% (95% confidence interval, 95.8%-98.2%). Thus, the anti-H. ducreyi LOS immune response is a significant diagnostic and epidemiologic indicator.