T cells
Neither. Alloreactivity has to do with a lymphocytes reacting to a foreign antigen. Positive and negative selection are processes of central tolerance which is to say that they deal with a T cell's ability to bind self-antigen.
Clonal selection is responsible for the proliferation of clones of effector and memory cells specific for an encountered antigen
Lymph node
A antigen
1. An antigen presenting cell presents antigen on Class II MHC to a Helper T cell activating it 2. At the same time a B cell that has taken up and degraded the same pathogen displays antigen on its class II 3. The activated helper T cell binds to the B cell releasing cytokines and activating it 4. The activated B cell proliferates and differentiates into: 1) memory B cells 2) antibody-secreting plasma cells that produce antibodies specific for the pathogen
neutralization of the antigen, agglutination or precipitation, and complement activation.
antigen processing and presentation
Yes. The first signal that a T cell receives from an antigen presenting cell (dendritic cell) is MHC presenting an antigen (foreign peptide). This gives the T cell specificity to this antigen.
Neither. Alloreactivity has to do with a lymphocytes reacting to a foreign antigen. Positive and negative selection are processes of central tolerance which is to say that they deal with a T cell's ability to bind self-antigen.
They proliferate due to their exposure to IL-2
Clonal selection is responsible for the proliferation of clones of effector and memory cells specific for an encountered antigen
Lymph node
Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies.
The glycoprotein CD4 is a co-receptor. A co-receptor is "a cell surface receptor, which, when bound to its respective ligand, modulates antigen receptor binding or affects cellular activation after antigen-receptor interactions." (MediLexicon)
Answer Class II MHC protein. Class II are found in membranes of antigen-presenting cells-phagocytic cells and lymphocytes. The liver performs phagocytosis and antigen presentation.
T cells receive 3 signals during activation:1. Major Histocompatibility Complex (MHC) presenting an antigen (foreign peptide) to the T cell receptor2. The co-stimulatory signal (B7 on the dendritic cell binding to CD28 on the T cell)The first signal ensures that the T cell is specific for the antigen it has been presented.The T cell cannot be activated without also recieveing the second signal. This is how the T cell checks that it has been presented an antigen by a "professional" antigen presenting cell.3. Cytokines (signalling molecules) are released by the dendritic cell - these cause the differentiation of the T cell
A antigen