Induction of latent immunological memory in genetically nonresponsive mice

Area of Science:

• Immunology
• Molecular Biology

Background:

• C57BL/10 mice display major histocompatibility complex-linked nonresponsiveness to hen egg white lysozyme (HEL).
• Priming with HEL in Freund's complete adjuvant (FCA) results in minimal to nonexistent secondary splenic plaque-forming cell responses to HEL.
• This nonresponsiveness presents a challenge for understanding immune priming mechanisms.

Purpose of the Study:

• To investigate whether concomitant immunization with a foreign antigen can overcome MHC-linked nonresponsiveness to HEL.
• To determine if T-cell and B-cell levels are primed in nonresponsive mice upon exposure to HEL.
• To explore the cellular basis of immune priming in the context of antigen-specific nonresponsiveness.

Main Methods:

• Mice were primed with HEL alone or with HEL and keyhole limpet hemocyanin (KLH) in Freund's complete adjuvant (FCA).
• Secondary immune responses were assessed following challenge with an HEL-KLH conjugate.
• Adoptive transfer experiments using fractionated spleen cells were conducted to identify primed cell populations.

Main Results:

• Concomitant priming with HEL and KLH led to an enhanced response to the HEL component upon secondary challenge.
• The enhancing effect was transferable via nylon wool nonadherent spleen cells from HEL/FCA primed animals.
• Adoptive transfer studies suggested that B cells were also primed in these animals.

Conclusions:

• Mice incapable of mounting a secondary response to HEL can still be primed at both T-cell and B-cell levels.
• Co-immunization with an unrelated antigen (KLH) can facilitate immune responses to an otherwise nonresponsive antigen (HEL).
• These findings have implications for understanding immune tolerance and developing strategies for enhancing responses to specific antigens.