Monocytes immune response

Decreases the production of lymphocytes and eosinophils in the blood by causing atrophy of the thymus gland blocks the release of cytokines, resulting in a decreased performance of T and B monocytes in the immune response. (This action, coupled with the anti-inflammatory action, makes the corticosteroids useful in delaying organ rejection in patients with transplants.)... 

A large number of cells are involved in the immune response and all are derived fiom the multipotential stem cells of the bone marrow. The predominant cell is the lymphocyte but monocytes-macrophages, endothelial cells, eosinophils and mast cells are also involved with certain immune responses. The two types of immunity (humoral and cell-mediated) are dependent on two distinct populations of lymphocytes, the B cells and the T cells respectively. Both the humoral and the cell-mediated systems interact to achieve an effective immune response. 

These are the eentral eells of the immune system as they are essential for activation of the other eells assoeiated with an effeetive immune response hy the secretion of peptide mediators termed eytokines. Cytokines produeed hy macrophages and monocytes are termed monokines whilst those produeed hy lymphocytes are termed lymphokines. TH eells express CD4 on their surfaee. 

Stress-related immune dysregulation also involves the synthesis of hormones including ACTH, growth hormone, and prolactin.14-17 Interestingly, it has also been demonstrated that various aspects of the immune response, for example., proliferation of B- and T-cells, cytokine production, antibody production, chemotaxis of monocytes and neutrophils, and natural killer (NK) cell cytotoxicity, can be affected by glucocorticoids (including cortisol) as well as peptides such as ACTH, CRH, endorphins, substance P, and somatostatin.1218... 

Immune responses are mediated through the lymphocytes called B cells and T cells. Lymphocytes are a particular type of white blood cell. White blood cells (leukocytes) are divided into granulocytes (neutrophils, 55-70% eosinophils, 1-3% and basophils, 0.5-1%) and agranulocytes (lymphocytes [B and T cells], 20-40% and monocytes, 1-6%). There are 5000-10,000 white blood cells per milliliter of blood, compared with five million red blood cells in the same volume. 

In monocytes stimulated with Toll-like receptor-triggering bacterial products, histamine inhibits the production of proinflammatory IL-1-like activity, TNF-a, IL-12 and IL-18, but enhances IL-10 secretion, through HR2 stimulation [26, 69]. Histamine also downregulates CD 14 expression via Hj receptors on human monocytes [70]. The inhibitory effect of histamine via Hj receptor appears through the regulation of ICAM-1 and B7.1 expression, leading to the reduction of innate immune response stimulated by LPS [71]. 

Finally, in this brief overview of lymphocyte defects, mention should be made of mutations affecting major histocompatibility-complex (MHC) Class II molecules. These mutations affect a multiprotein transcription factor complex that regulates the expression of MHC Class II molecules (121). Affected patients have undetectable levels of MHC Class II antigens HLA-DP, DQ, and DR on the surface of monocytes and B cells. Lack of these antigen-presenting molecules leads to impaired immune response. Affected individuals have moderate lymphopenia with a severely reduced number of CD4+ T cells and normal or increased numbers of CD8+ T cells. Since MHC molecules in the thymic epithelium play a key role in positive and negative selection of primitive T cells, selection of competent T cells is also affected in the absence of MHC Class II antigens. 

Chen LY, Lin YL, Chiang BL. Levamisole enhances immune response by affecting the activation and maturation of human monocyte-derived dendritic cells. Clin Exp Immunol 2008 151(1) 174-81. 

Mechanism of Action A biologic response modifier that induces activation of macrophages in blood monocytes to phagocytes, which is necessary in the body s cellular immune response to intracellular and extracellular pathogens. Enhances phagocytic function and antimicrobial activity of monocytes Therapeutic Effect Decreases signs and symptoms of serious infections in chronic granulomatous disease. Pharmacokinetics Slowly absorbed after subcutaneous administration. Half-life 0.5-1 hr. 

Endogenous histamine has a modulating role in a variety of inflammatory and immune responses. Upon injury to a tissue, released histamine causes local vasodilation and leakage of plasma-containing mediators of acute inflammation (complement, C-reactive protein) and antibodies. Histamine has an active chemotactic attraction for inflammatory cells (neutrophils, eosinophils, basophils, monocytes, and lymphocytes). Histamine inhibits the release of lysosome contents and several T- and B-lymphocyte functions. Most of these actions are mediated by H2 or H4 receptors. Release of peptides from nerves in response to inflammation is also probably modulated by histamine, in this case acting through presynaptic H3 receptors. 

IFN-y modulates a number of components of the immune response. This is the only type II IFN whereas there are more than 20 types of type I IFNs (IFN-a, IFN-(3, IFN-w and IFN-t). It is not related to type I IFNs, has separate receptors and is encoded by a different chromosomal locus. IFN-y is produced by activated T lymphocytes (THi and CD8+ cells), NK cells, B cells, NKT cells and professional APCs. It promotes the activity of cytolytic T lymphocytes, macrophages and NK cells. The cell self-activation and activation of nearby cells in part may result from IFN-y production by professional APCs, which include monocyte/macrophage and dendritic cells. The early host defense against infection is likely to utilize IFN-y secreted by NK and professional APCs. In acquired immune responses, T lymphocytes are the major source of IFN-y. 

---