Figure 7

Schematic drawing of the basic "tissue control unit," which consists of monocyte-derived cells (M), vascular pericytes (P), and autonomic innervation (AI, dashed arrow), and the involvement of other components of the tissue control system (solid arrows). Monocyte-derived cells physically interact with adjacent epithelial (Ep) and endothelial cells (En) through the basement membranes (dotted lines), and influence pericytes, which secrete intercellular vesicles (ICV). These vesicles collapse into the so-called empty spikes (ES) releasing their content (growth factor/cytokine) after reaching target cells. The activity of pericytes is stimulated or inhibited by autonomic innervation (+ or -) which controls quantitative aspects of tissues. Interaction of monocyte-derived cells with endothelial cells may stimulate homing of T lymphocytes (T) and monocyte-derived dendritic cell precursors (DCP; also known as veiled cells) differentiating into mature dendritic cells (DC). The dendritic cell precursors and T cells interact themselves and stimulate advanced differentiation of epithelial cells. IgMs regulate early (IgM¹), mid (IgM²), and late differentiation (apoptosis) of epithelial cells (IgM³), and IgG associates with aged cells (see Fig. 6). Dominant role in the regulation of qualitative aspects of tissues belongs to monocyte-derived cell system (including intraepithelial DCP and mature DC), which is supposed to regulate properties of tissue specific cells, including expression of ligands for intraepithelial T cells and autoantibodies. Monocyte-derived cells also carry the "stop effect" information encoded at the termination of immune adaptation, which determines the highest state of epithelial cell differentiation allowed for particular issue. For details see Ref. [9,10].