NON-SPECIFIC AND SPECIFIC RECOGNITION MECHANISMS OF BACTERIAL AND MAMMALIAN CELL MEMBRANES

Abstract

The recognition of bacteria by mammalian cells, or vice versa, involves specific, i.e. ligand-receptor interactions, and nonspecific, physicochemical factors, e.g. surface charge and hydrophobicity. Specific interactions can be of non-immunological character, viz. carbohydrate-specified, lectin-like cell-cell association, conveyed by bacterial adhesins, e.g. fimbriae or mammalian cell appendages for instance on macrophages. Other bacterial adhesins bind to receptor substances adsorbed onto the mammalian cells like serum proteins, or molecules being part of the histocompatibility antigen complex, e.g. β2-microglobulin. Immunological recognition comprises association between antibody or complement-coated (opsonized) particles with Fc- and C3b-receptors on phagocytic cells (polymorphonuclear leukocytes, macrophages, Kuppfer cells). On the other hand, these apparently specific interactions between ligands and receptors identified at the molecular level, also achieve general physicochemical alterations. The present communication reviews experimental data on the dualistic character of the association between bacteria and animal cells, i.e. the interplay between specific and non-specific factors that promote or counteract cell-cell recognition.