Immunological activity difference between native calreticulin monomers and oligomers.

Area of Science:

• Immunology
• Cell Biology
• Protein Chemistry

Background:

• Recombinant calreticulin (rCRT) shows increased immunological activity due to self-oligomerization.
• Native CRT (nCRT) can oligomerize in vitro under stress, but intracellular oligomerization and its immune effects are unknown.

Purpose of the Study:

• To investigate CRT oligomer formation within cells under stress conditions.
• To compare the immunological activities of native CRT monomers and oligomers.

Main Methods:

• CRT oligomer formation was induced in transfectant cells using heat and low pH.
• Murine monomeric nCRT (MnCRT) was treated in vitro to obtain oligomeric and monomeric nCRT mixtures (OnCRT).
• Immunological activity was assessed by antibody recognition, IgG production in mice, and cytokine secretion from bone-marrow derived dendritic cells (BMDCs).

Main Results:

• CRT oligomers were successfully formed in cells under heat and low pH stress.
• OnCRT demonstrated enhanced recognition by specific monoclonal antibodies compared to MnCRT.
• OnCRT induced CRT-specific IgG production and significantly higher secretion of TNF-α, IL-6, and IL-12p40 from BMDCs than MnCRT.

Conclusions:

• Soluble CRT oligomerization may occur in vivo under pathophysiological conditions like ultrahyperpyrexia.
• CRT oligomers possess exaggerated immunostimulating activities compared to monomers.
• CRT oligomerization could contribute to inflammatory responses.