Toll-like receptors (TLRs) and mannan-binding lectin (MBL): On constant alert in a hostile environment

Abstract

In the beginning were neither B cells nor T cells nor antibodies, but innate immune defense alone. The primary functional theme of innate immunity is the distinction between self and non-self, which is maintained by a vast number of cellular and subcellular components. In this context, the immense importance of the Toll-like receptors (TLRs) is well established. Positive (Darwinian) selection seems to be acting on the ligand-binding domains of these molecules, suggesting a selection pattern similar to that previously observed in the MHC proteins. In sharp contrast to TLRs, the biological significance of mannan-binding lectin (MBL) is controversial, and, concerning humans, it has been suggested that low concentration of MBL in serum represents a selective advantage. In this mini-review, based on a doctoral thesis, evolutionary aspects of TLRs and MBL are discussed.

Key words::

• Innate immunity
• MBL
• molecular biology
• positive selection
• recognition
• TLRs

Acknowledgements

I would like to express my gratitude to Professor Kristina Nilsson Ekdahl, Linnaeus University, Kalmar, and Uppsala University, Uppsala, Sweden, and Professor Göran Andersson, Swedish University of Agricultural Sciences, Uppsala, Sweden, who both supported me during the writing process.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.