| | Re: Antibodies in human body
Dendritic cells are generated by the expansion of proliferating precursors found in the peripheral blood such as adherent PBMC or elutriated monocytic fractions cultured (for 7-10 days with GM-CSF (50 ng/ml) and IL-4 (20 ng/ml). These dendritic cells have the characteristic phenotype of immature cells (expression of CD1, CD80, CD86, CD40 and MHC class II antigens). Treatment with activating factors, such as TNF-α, causes a rapid change in surface phenotype (increased expression of MHC class I and II, costimulatory and adhesion molecules, downregulation of FCγRII, upregulation of CD83). These changes correlate with increased antigen-presenting capacity and with functional maturation of the dendritic cells. This cells treated for 1-3 days with D-SLAM (Dendritic Enriched Secreted Lymphocyte Activation Molecule) or LPS generate cytokines, in particular IL-12, important in the initiation of T-cell dependent immune responses. IL-12 strongly influences the development of Th-1 helper T-cell immune response, and induces cytotoxic T and NK cell function. Phenotypically, human DC are distinguished by their expression of CD1a and CD11c. CD4+CD1a+CD11chigh and CD4+CD1a-CD11clow comprise the conventional myeloid lineage human DC while the lymphoid pDC lineage consists of CD4+CD1a-CD11c- cells. Though these distinct subsets of DC have been clearly defined in humans, it should be noted that DC exhibit great plasticity, and it is possible that these cells may exist as a continuum of cell types rather than as separate entities. Three major families of cell surface antigens can be identified on monocytes : adhesion molecules, molecules involved in antigen presentation, and Fc receptor. Modulation of the expression of MHC class II antigens and other costimulatory molecules, such as B7 and ICAM-1, may result in changes in the antigen presenting capacity of monocytes and ability to induce T cell activation. Increase expression of Fc receptors may correlate with improved monocyte cytotoxic activity, cytokine release and phagocytosis. Human peripheral blood monocytes progressively lose viability when cultured in absence of serum or other stimuli. Their death results from internally regulated process (apoptosis). Addition to the culture of activating factors, such as TNF-α (100 ng/ml) dramatically improves cell survival and prevents DNA fragmentation. In addition, B cells progenitor (CD45R-CD19+) and even some mature B cells, can be source of macrophage, in which PU.1 (ets family transcription factor), required for the development of multiple lineages of the immune system, at different concentrations regulate the development of B lymphocytes as compared with macrophages. A low concentration of PU.1 protein induces the B cell fate, whereas a high concentration promotes macrophage differentiation and blocks B cell development. For as stated above, I confirm as tells in my mail "specialized macrophage" for indicate a particular phagocyte cell with anatomical and functional characteristics of “macrophage-like” monocytes- or B cell-derived. From monocytes line (CD11c+, CD13+, CD33+, CD14+) of the peripheral blood (blood precursor) originate the macrophages (in presence of M-CSF), Interstitial Dendritic Cell (IDC) in presence of GM-CSF/IL-4/TNF-α, and dendritic cell of the Langherans (LDC) phenomenon observed in the repopulation of the cutaneous LDCs after phlogosis, by circulating monocytes. IDCs are the professional APC that present antigen and induce B cell differentiation, but also happens through the interaction macrophage-B cell, for the B cell activation to answer at polysaccharide thymic independent antigen. Particularly, macrophage present antigen at B cell when antigen, by itself, not is able to activate directly B cell. Recently, utilizing multiphoton intravital microscopy on lymph nodes, has been observed that macrophages of the mouse lymph node subcapsular sinus facilitate B cell activation in vivo by collecting and displaying native antigen. In last, but not list, interstitial DCs monocytes-derived it’s only the able to induce the differentiation of naive B cells into immunoglobulin-secreting plasma cells.