Objective: To examine whether and at what stage mucosal immune responsiveness is impaired during HIV-1 infection.
Design: Intestinal and systemic antibody-secreting cell (ASC) responses were examined in eight HIV-1-infected volunteers and 10 seronegative control subjects after oral cholera and parenteral tetanus vaccinations.
Methods: ASC numbers were determined before and after booster vaccinations by the enzyme-linked immunospot (ELISPOT) technique. This technique was performed on cell suspensions obtained from enzymatically dispersed duodenal biopsies and from peripheral blood.
Results: Oral cholera vaccination evoked ASC responses in the intestinal mucosa of six out of eight HIV-1-infected volunteers, including patients with advanced disease and very low levels of circulating CD4+ T cells. The intestinal cholera ASC responses in HIV-infected volunteers were comparable to those in uninfected controls with regard to both magnitude and distribution of antibody classes. Most HIV-infected volunteers with only moderately reduced CD4+ T-cell counts also responded with vaccine-specific ASC in the blood, whereas none of the patients with < 200 x 10(6)/l CD4+ T cells per litre blood had detectable circulating ASC.
Conclusion: These findings indicate that mucosal humoral immune responsiveness to a T-cell dependent antigen is maintained in HIV-infected individuals, despite concomitant systemic humoral hyporesponsiveness.