Antigen-specific, IgE-selective unresponsiveness induced by antigen-liposome conjugates - Comparison of four different conjugation methods for the coupling of antigen to liposome

Background: We have previously reported that ovalbumin (OVA) coupled with l iposome via glutaraldehyde (GA) induced OVA-specific- and IgE-selective unr esponsiveness in mice. Methods: In this study, OVA-liposome conjugates were made using four different coupling protocols: via GA, N-(6-maleimidocaproy loxy) succinimide (EMCS), disuccinimidyl suberate (DSS) and N-succimidyl-3( 2-pyridyldithio)propionate (SPDP) and the induction of antigen-specific IgG and IgE antibody production was investigated for each. In addition, antige n-specific cytokine production by spleen cells of mice immunized either wit h OVA-liposome or with OVA adsorbed with aluminum hydroxide was investigate d. Results: OVA-liposome conjugates coupled via GA or DSS did not induce an ti-OVA IgE antibody production but induced substantial anti-OVA IgG antibod y production. On the other hand, the induction of anti-OVA IgE unresponsive ness by OVA-liposome conjugates coupled via EMCS or SPDP was incomplete. Th e amount of interleukin 4 (IL-4) produced by spleen cells stimulated in vit ro with OVA correlated well with anti-OVA IgE antibody production in donor mice. However, the production of no other cytokine, i.e., IL-2, IL-5, IL-10 or interferon-gamma, was correlated with in vivo IgE antibody production. Conclusion: OVA-liposome coupled via GA or DSS induced complete suppression of anti-OVA IgE production. The results in this study further suggest that the regulation of IgE antibody production does not neccessarily correlate with so-called Th1 cytokine production. Copyright (C) 1999 S. Karger AG, Ba sel.