Dendritic Cells Study Guides

‭Dendritic cells‬ ‭ hey are composed of Langhéran cells, interdigitate cells, veiled cells found in the lymphatic‬ T ‭channels, interstitial dendritic cells highlighted in certain organs. We exclude from these dendritic‬ ‭cells of myeloid origin the follicular dendritic cells which we find in the lymphoid follicles because‬ ‭these follicular dendritic cells have a mesenchymal origin and other part we also exclude thymic‬ ‭dendritic cells (of the Thymus) which have a lymphoid origin.‬ ‭ hese dendritic cells of myeloid origin have characteristics in common:The potentiality to‬ T ‭incorporate the antigen and express it on the surface of the cell, the ability to migrate selectively‬ ‭across tissues. The ability to interact and stimulate the T-type response. It is therefore above all a‬ ‭functional definition.‬ I‭ n MO:‬‭the morphology (phenotype) is variable depending‬‭on their location.‬ ‭-‬ ‭there‬‭Langherans cell found‬‭at the level of the epidermis‬‭has a multilobed nucleus. In the In‬ ‭the cytoplasm, so-called “Birbeck” eosinophilic granulations are highlighted. These cells do not‬ ‭contain melanosomes although they are in the epidermis.‬ ‭-‬ ‭THE‬‭dendritic cells of the dermis‬‭:have a notched nucleus,‬‭fine chromatin, and cytoplasmic‬ ‭boundaries are poorly defined.‬ I‭ n ME:‬ ‭-‬ ‭the Langhérans cell has few intracellular organelles. This allows us to show that these‬ ‭Birbeck granules are the joining of membranes between which we have particles opaque to‬ ‭electrons.‬ ‭-‬ ‭there dendritic‬‭cell of the dermis‬‭:has the characteristics‬‭of a cell metabolically more‬ ‭active with more developed synthesis equipment (REG, golgi apparatus, mitochondria) and they do‬ ‭not contain Birbeck granules.‬ ‭In these dendritic cells we do not detect myeloperoxidase, we will find non-specific esterases, acid‬ ‭phosphatase. The molecular expressionThe surface area varies depending on the location:‬ ‭-‬ ‭in the‬‭Langhérans cell‬‭HLA class II molecules are poorly‬‭expressed even though they are no‬ ‭longer in the dendritic cells of the dermis or interdigitate cells‬ ‭ adherins areThe molecules that play a role in cell adhesion are strongly expressed in the‬ C ‭Langhérans cell and less in the dendritic cells of the dermis or the cells interdigitates‬ ‭➔‬ ‭This is explained by the fact that we have in the MOH the precursors of the cellsthe dendritics‬ ‭which pass into the blood, go to the level of the dermis and then this cell dendritic cell of the‬ ‭dermis will reach the epidermis to become a Langhérans cell. Has a moment it will be in contact‬ ‭with an antigen: there will be an inflammatory reaction local and the Langhérans cell will‬ ‭capture the antigen, leave the epidermis and to leave it there must be a reduction in cell adhesion‬ ‭and therefore a reduction in the expression of cadherins. The Langhérans cell will come to‬ ‭theThe dermis is a cell that will be more active because you will have to degrade and shape the‬ ‭antigen to be able to present it to the T lymphocytes. In the dermis, the dendritic cell of the‬ ‭dermis will leave the dermis through the lymphatic vessels and then it will go to the lymph node‬ ‭where initially this dendritic cell is called veiled cells because the cytoplasmic expansions are‬ ‭very numerous and when this cell penetrates the lymph node parenchyma it will become an‬ ‭interdigitated cell .‬