Thus, the processed antigen is seen as “not-self,” i. e., “foreign.”
The key event…
A processed antigen in an MHC is seen by a TCR. This “viewing” occurs in the ternary complex.
The TCR asks the MHC, “Are you me?” and receives an affirmative answer, “Yes.” Here the TCR looks at the MHC histotope.
The TCR asks the processed antigen, “Are you me?” and receives the negative answer, “No!” Here the TCR uses its paratope and looks at the epitope.
The key event…
A processed antigen in an MHC is seen by a TCR.
The TCR asks the MHC, “Are you me?” and receives an affirmative answer, “Yes.”
The TCR asks the processed antigen, “Are you me?” and receives the negative answer, “No!”
The basis of immunogenicity…
Chemical composition and heterogeneity
Epitopes for B-cells versus T-cells
By examining myoglobin one can see that the Ag’s seen by B-cells and T-cells are different. B-cells see a continuous or discontinuous series of amino acids; by some circumstance, amino acid residue 109 has never been a part of an epitope for any monoclonal antibody; yet residue 109 is always part of the processed antigen seen by a TCR.
TH have CD4 which interacts with MHC-II; thus, CD4+ T-cells are “MHC-II restricted.”
TH cells are “helper cells” that send signals (via cytokines and surface proteins) to other cells of the immune system. The TH cells function as the “brain” of the immune system.
There are two classes of T-cells
TC have CD8 which interacts with MHC-I; thus, CD8+ T-cells are “MHC-I restricted.”
TC cells become cytotoxic T lymphocytes (CTL’s) which attack “altered self-cells (e. g., infected cells.) “Altered self-cells” are also called “target cells.” They are the targets for the CTL’s cytotoxicity.
Experimental systems… viz. “haptens”
Hapten: a low molecular-weight molecule that can be made immunogenic by conjugation to a suitable carrier…
Experimental systems… viz. “adjuvants”
Adjuvants: A substance that non-specifically enhances the immune response to an antigen