View All Abstracts for Session 14
62 Male Genital Tract Responses Elicited by Systemic Immunization
Z. Moldoveanu*, M. S. Pate, and J. Mestecky
Univ. of Alabama at Birmingham, USA
Background: Immune responses in the genital tract maybe important in prevention of sexually transmitted HIV infections. Genital tract displays unique features not shared by other mucosal sites: IgG, not IgA, is the dominant Ig, and local infections or immunization induce limited responses. Our objective was to evaluate the form of antigen effective in generating immune responses in human male genital tract. Selection of vaccines was based on type of antigens with potential to be used for delivery or as adjuvants for HIV antigens.
Methods: Inactivated influenza virus, pneumococcal polysaccharides (PnPs), or tetanus-diphtheria toxoids (TT-DT) were administered intramuscularly (I.M.) to 35 healthy male volunteers. Antibody-secreting cells (ASC) were enumerated in peripheral blood collected prior to and at 1 week post injection. Vaccine-specific and total antibody levels were determined by ELISA in semen, sera, nasal fluids, and saliva collected before and at 7, 28, and 42 days after immunization.
Results: Numbers and Ig isotype distribution of vaccine-specific ASC in circulation varied depending on the nature of antigen. When expressed as percentage of the total number of cells secreting a specific isotype, bacterial toxins induced mostly IgG, PnPs predominantly IgM and IgA, and influenza virus approximately equal proportions of IgG- and IgA-ASC. Increases of vaccine-specific antibodies measured in sera paralleled those observed for ASC. In seminal fluid, influenza vaccine induced high levels of antibodies, mainly IgG, whereas the almost exclusively IgG responses anti-TT and DT were rather low. Immunization with PnPs, elicited an IgA response in seminal plasma of all volunteers and IgG and IgM in 8/10. Kinetics and characteristics of antibodies in semen were different from those of other secretions.
Conclusions: Similar distribution of vaccine-induced antibodies was determined in seminal fluid and in corresponding sera of immunized volunteers with microbial protein, polysaccharide, or toxoid antigens, suggesting that the majority of antibodies induced by systemic immunization in human male genital secretions are of plasma origin. In semen, unlike in other secretions, antibodies could be induced by systemic vaccination. Therefore, injectable vaccines could protect against pathogens entering through the genital tract
Contact Author about this Abstract
