Mechanical immunology: every mechanical crushing of a cell in living organisms results in an immunological reaction

Throughout a living organism, the cells are constantly exposed to mechanical stresses. Because of these stresses, cells are continually broken down into various organs and structures. Thus, internal components of the cell that do not appear in the serum or extracellular space under stress-free conditions are released. These components, according to the ideas described here, can lead to an immune reaction and a subsequent inflammatory reaction. For these reasons the organism attempts to prevent the destruction of cells and employs a variety of mechanisms to try and achieve this aim. Apoptosis, i.e. suicide by the damaged cell, is one such mechanism as is the work of phagocytes that appear in the most varied organs. Further protection for the cell consists in the separation of the spaces in which the destruction of cells takes place by means of membranes and basal membranes. A further conclusion, which follows from this concept, is the separation of the CD4 and CD8 T-cell receptor spectra. Whereas CD4 T receptors recognise extracellular antigens the CD8 T-cell receptors recognise intracellular antigens. Conversely, the body's own extracellular structures do not lead to a reaction via the CD4 cells, the corresponding T-cell populations are eliminated and the body's own intracytoplasmic structures do not lead to a reaction via the CD8 cells. Each of the reverse combinations between structures and cell populations should lead, however, to an immune system reaction. (C) 2004 Elsevier Ltd. All rights reserved.