Background
Toll-like receptors (TLRs) have a crucial role in early host defence against invading pathogens. They recognize specific molecular patterns that are present in microbial and viral components, whereas several endogenous molecules seem to be placed among their expanding group of ligands. The CD91 receptor (low-density lipoprotein receptor-related protein [LRP1] or alpha 2-macroglobulin receptor [A2MR]) is a multifunctional receptor that recognizes hsp-chaperoned peptides, which are processed and presented by the MHC class I and MHC class II molecules. So far, there is an increasing evidence that the receptors of innate immunity also play an important role in acquired immunity.