Question

11. Describe the process of antigen recognition/presentation for T-cell subsets. Include the following in your response:

a. Role of activation & antigen presenting cells

b. MHC molecules involved

c. Restricted recognition

d. Co-receptors

e. Signaling

f. Cytokines stimulated or responded to

g. Cells stimulated

Answer 1

Antigen presentation is central to specific immunity. ... Antigens are presented by a set of cell surface proteins called major histocompatibility (MHC) proteins . Their main function is to bind peptide fragments and display them on the cell surface for recognition by the appropriate T cells.

a) Critical role for activation of antigen-presenting cells in priming of cytotoxic T cell responses after vaccination with virus-like particles. ... Virus-like particles (VLPs) are known to induce strong Ab responses in the absence of adjuvants. In addition, VLPs are able to prime CTL responses in vivo.

b) The major histocompatibility complex and its functions. The function of MHC molecules is to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells.

c) MHC-restricted antigen recognition, or MHC restriction, refers to the fact that a T cell can interact with a self-major histocompatibility complex molecule and a foreign peptide bound to it, but will only respond to the antigen when it is bound to a particular MHC molecule.

d)A co-receptor is a cell surface receptor that binds a signaling molecule in addition to a primary receptor in order to facilitate ligand recognition and initiate biological processes, such as entry of a pathogen into a host cell.

e)Thus, T cells require at least three “types” of signals to expand and exert their effector activities. The first one is direct antigen recognition. ... However, a third signal is also required to modulate T cell differentiation into different subsets that will control the type of immune responses.

f) Cytokines. The cytokine pattern that is released from the cell depends primarily on the nature of the antigenic stimulus and the type of cell being stimulated. Cytokines compromise leukocytes to respond to a microbial stimulus.

g) Cell stimulation. Serial dilutions of PTH1R ligands were prepared at 1000 × desired final concentration. At time 0, 1 μL of vehicle or ligand concentrate was added to the 1 mL of serum-free media in each well and the plates were incubated for 5 min at 37 °C. PMA at a final concentration of 200 nM was added to one well of each plate as a positive control.