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Carrier-induced, hapten-specific suppression: a problem of antigen presentation?
X Renjifo1, S Wolf, P P Pastoret
1Département de Biologie Moléculaire, Université Libre de Bruxelles, Rhode-Saint-Genèse, Belgium.
Journal of Immunology (Baltimore, Md. : 1950)
|July 22, 1998
Summary
Prior immunity can suppress specific antibody responses. This study suggests that defective antigen presentation by B cells, not T cells, causes this "epitopic suppression," which can be prevented by dendritic cell injection.
Area of Science:
- Immunology
- Cellular immunology
- Humoral immunity
Background:
- Prior immunity to a carrier protein modulates immune responses to haptens linked to it.
- Carrier/hapten-carrier immunization suppresses IgG2a anti-hapten antibody production without affecting anti-carrier antibodies.
- The mechanism of this epitopic suppression remains unclear, but a deficiency in Th1 cell activation is suspected.
Purpose of the Study:
- To investigate the mechanism underlying epitopic suppression.
- To determine the role of antigen-presenting cells (APCs) in epitopic suppression.
- To test the hypothesis that B cells present the hapten-carrier conjugate in pre-immunized animals.
Main Methods:
- Immunizing mice with a hapten-carrier conjugate.
- Injecting mice with syngeneic dendritic cells (DCs) pulsed with the antigen.
- Administering interleukin-12 (IL-12) alongside DCs.
Main Results:
- Injection of DCs pulsed with antigen prevented epitopic suppression.
- IL-12 administration also prevented epitopic suppression.
- These findings suggest that defective antigen presentation contributes to epitopic suppression.
Conclusions:
- Epitopic suppression may result from inadequate antigen presentation.
- Dendritic cells and IL-12 can overcome this suppression.
- The nature of APCs influences T helper cell development and subsequent immune responses.