Dendritic cells functions and types
- 2. Introduction • named for their special spine like projections • Component of innate immune system, elicit primary immune response • Function: Antigen presentation and activation of T cells. Inducing and maintaining immune tolerance. Maintain immune memory in tandem with B cells. To process antigen material and present it on the surface to T-cells, thus functioning as antigen-presenting cells
- 3. Source : pluripotent hematopoietic stem cells Location Dendritic cells -skin ( Langerhans cells,dermal dendritic cells) inner lining of the nose, lungs, stomach and intestines. Blood
- 4. Function of DC : • Capture, process, present antigens—APC • Stimulate T or B lymphocytes—mature DC • Induce immune tolerance—immature DC
- 5. TYPES OF DENDRITIC CELLS Langerhans cells Dermal dendritic cells Melanocytes Merkel cells
- 6. Langerhans cells • Present in epidermis,dermis,thymus,tonsils,lymph nodes, epithelia of oral and genital mucous membranes. • Derived from mesenchymal precursors in bone marrow • Constitute 2% to 8% of total epidermal cell population.
- 7. Dermal dendritic cells • Non-indigenous DCs precursors characterized by highly developed ER(plasma cell like appearance) enters the skin cutaneous immune mechanism,especially in antigen presentation , stimulation of T cell response phagocytosis regulation of epidermal differentiation
- 8. MELANOCYTES • Dendritic cells that synthesize and secrete melanin containing organelles called melanosomes. • Melanocytes are more abundant in skin of face and male genitalia upto 2900/mm2 than on trunk upto 1250/mm2 • As a rule greater amount of melanin is present in basal keratinocytes than in melanocytes
- 9. MERKEL CELLS • Slow adapting type1 mechanoreceptors in sites of high tactile sensitivity • Location: basal layer of epidermis • In hairy skin & glabrous skin of digits, lips, regions of oral cavity , outer root sheath of hair follicle • They may enhance or induce the excitability of sensory nerve endings via release of neuropeptides.