Activation of CD4+ T cells fits into a ______________ model.
Two-signal
Interaction of the _________and __________ on the T cell with ___________ and __________ on the APC provides stimulus for the 1st signal/induction/activation of CD4+ T cells.
TCR and CD28
MHC complex (B7) and CD80/86
The 1st downstream signal transduction, leading to T cell activation emanates from the ____________.
TCR and CD28
___________________________ serves as the second signal in T cell activation.
The receptors on the antigen are stimulated by some stimuli resulting in co-stimulation
____________is a co-stimulatory molecule expressed constitutively on naïve T cells.
CD28
____________ expressed on the antigen presenting cells serve as co-stimulators for naïve T cells.
CD80 and CD86
The TCR is associated with CD3 and forms ____________ complex.
the TCR-CD3
CD__ is present on helper T cells and CD__ is present on cytotoxic T cells
4
8
CD4 works as a monomer with four ________ in its extracellular protium.
Ig domains
CD8 functions as a dimer involving either a_______________ or __________________.
α and αβ chains or two identical α chains
The specificity of antigen recognition T cell response is dependent on the interaction between the _____________, ________________ and ________________.
TCR, the MHC peptide complex and the APC
The binding of antigen to antibody involves the formation of multiple _____________bonds between the antigen and ______________of the antibody.
non-covalent
amino acids
Antigen-antibody complex results from ____________bonding, ____________bonding, ______________bonds and ________________bonds.
Hydrogen
Electrostatic
van der Waals
hydrophobic
The antigens are _____________dimensional structures.
three
Different antibodies to an antigen often bind to overlapping_____________.
epitopes
Technically, antibodies may be produced against any _______________but this is usually not the case.
Part of the antigen
Certain areas of the antigen are particularly antigenic and, that the majorities of the antibodies bind to these regions which are called________________ regions.
Immunodominant
What is HLS?
MAJOR HISTCOMPATIBILITY COMPLEX in humans
The ability to discriminate (Self versus Non-Self) is achieved through ______________.
MHC = MAJOR HISTCOMPATIBILITY COMPLEX
All antigens, both self and non-self, are recognized by T cells in the context of the______________.
MHC
(T/F) CD4+ cells and CD8+ cells recognize antigens similarly.
False (differently)
Helper T cells (CD4+) recognize antigens in conjunction with MHC class _____molecules.
II
Cytolytic T cells (CD8+) antigens in context of MHC class _____ molecules.
I
During embryogenesis T cells recognizing _____________in the context of MHC molecules are eliminated.
self antigens
During embryogenesis, T cells potentially recognizing _____________antigens in the presence of MHC molecules are retained.
foreign
Auto-immune disease is caused by a breakdown in_________________________________________.
the elimination of self-recognizing T cells
Failure to recognize foreign antigens results in __________________.
immunedeficiency
MHC molecules have evolved from the same gene as _______________and _____________molecules
Immunoglobulins and T cell receptor
MHC class I and class II molecules have different _____________, ________________ and ______________.
structure, distribution and function
MHC class I molecules include _____________________________.
HLA-A, HLA-B and HLA-C
MHC class II molecules include_______________________________.
HLA-D, HLA-DR, HLA-DP and HLA-DQ
MHC class III molecules include_________________.
complement system
HLA (MHC) Class I Molecules (HLA-A, HLA-B, HLA-C) are found in what cells?
Ubiquitous on virtually every cell
What are the functions of HLA (MHC) Class I Molecules (HLA-A, HLA-B, HLA-C) ?
Present processed antigenic fragment to CD8+ T cells
Restrict cell-mediated cytolysis of virus-infected cells (may be the main reason for their presence on every cell in the body)
HLA (MHC) Class II Molecules (HLA-D, HLA-DR, HLA-DP, HLA-DQ) are found in what cells?
Restricted to immune-competent cells
Particularly they are present on B cells and macrophages
What is the function of HLA (MHC) Class II Molecules (HLA-D, HLA-DR, HLA-DP, HLA-DQ)?
Present processed antigenic fragments to helper T cells (CD4+)
Recognition of antigenic fragment by the TCR on the surface of CD4+ cells, resulting in the initiation of immune response.
The initiation of immune response is characterized by the proliferation of ___________and the secretion of a battery of______________.