Bmsc210 final p3

• -Hapten PLL doesn't evoke immune response
• -after immunization to BSA, PLL-BSA is able to precipitate
• -after this PLL will precipitate serum on its own.
• - Thus the antibody could bind PLL and yet PLL could not induce the formation of antibody.
• -proved binding of antigen to antibody-like receptors of the precursor cell doesn't induce production of this antibody

-Antigen supposedly binded directly to precursor cell

• - did not explain how haptens could bind to antibodies(precipitation) but not induce antibody production(PLL-BSA)
• -proof that B-cells and T-cells are need to induce response(irradiated mice)

A substance that can induce antibody production

• -small molecules do not elicit immune responses (hapten)
• -can still be rather larger than the size of an amino acid

• -small molecules that cannot elicit immune responses
• -some macromolecules haptens exist that can bind antigens but do not produce immune response which is confusing

• -immunogenic macromolecule that are conjugated to haptens
• -If a hapten bound to one foreign substance elicits an immune response it will do so if found on another even if the other is non-immunogenic

Removal of thymus

unable to form immune response

bone marrow cells AND thymus cells(thymocytes)

• -T cell and B cell both bind to antigen from opposite sides
• -absence of response to PLL would be due to lack of PLL specific T helper to complete the bridge
• -PLL-BSA is recognized because there are many BSA specific T helpers so b binds to PLL side and T helper binds to BSA side
• Downfall:
• helper CD4+ T cells do not bind to antigens they bind to class II MHC bound proteins

• -B cells recognize specific antigens and engulf them through endocytosis, digest them and display antigen specific proteins on their Class II MCH structures.
• -T helper cells then bind onto said proteins and give signals to B cell for induction

-if PLL B cell engulfs PLL-BSA it can display BSA on MHC II and be activated by BSA T CELL creating PLL anti bodies

-receptor-bearing precursor cell arises from a stem cell with out receptors

-if the cell, when it first expresses a receptor, interacts with antigen, it will die (usually a self antigen because they are always present)

-Cells with receptors that do not interact with a self antigen will not die, and will mature into a different state that is inducible

• -when an antigen interacts with a B cell before maturity it results in the death of the B cell.
• -ensuring that anti-self B cells are eliminated

• The area on an antigen molecule complementary to an antibody molecule
• ex: MSA and RSA(mouse/rat serum albumin)

the ability of an antibody to precipitate antigens with epitopes in common

• -when a foreign antigen is cross reactive with a self-antigen autoantibodies can be created if the self-B cells have not all been weeded out
• -B cells can mistake cross reactive antigens for each other

-this is viable for both theories of B-T Cell collaboration

• -group A streptococci cross react with heart tissue
• -development of rheumatic heart disease is believed to be due to an autoimmune response to heart tissue following such an infection

-Rabbit thyroglobulin cross-reacts with turkey thyroglobulin

• -T_h Helper cells
• -Bears Thy1 antigen which activates B cells to produce progeny
• (B cells die if they interact with antigens and no CD4 T cells bond)
• -Bond to MHCII (macrophages/B cells)

exclusive

• leprosy
• Mycobacterium leprae

• tuberculosis
• Mycobacterium tuberculosis

HIV-1

visceral leishmaniasis

toxin neutralization

• -caused by T_h2 CD4 cells that inhibit cell mediated immunity(DTH) when antibodies are produced
• -caused mainly by secretion of IL4 which increases IgG and IgE response

• -caused by abnormal T_h1 CD4+ cells that inhibit antibody production when cell-mediated immunity is induced
• -mainly caused by IFNy

A cell mediated immune response

10,000

• -a particular growth hormone for T cells
• -one T cell, stimulated with antigen in the presence of IL2, will give rise to upwards of a million identical cells

• -Molecules secreted by CD4 T cells after bonding to B cells
• -molecules are normally delivered to target cells when the producing cell binds to the target cell with its receptor
• -either positively or negatively regulate the growth and differentiation of other cells, including other T cells
• -Different T cell secrete different Cytokines

IL2(growth Factor for T cells)

IFN-y(Can prevent viral multiplication and activate Macrophages)

-These functions suggest a central role for Th1 cells in cell-mediated immunity

Mycobacterium leprae 

Mycobacterium tuberculosis 

HIV-1

• -generated upon viral infection,
• -often deliver IFNy to and are cytotoxic for virus-infected cells.
• -a central component of the cell-mediated response.

macrophages activated by IFN-y

IL4: increases IgG and IgE responses

IL10

-These functions suggest a central role for T_h2 cells in Humoral immunity

• IFNy-activation of macrophages/AVP
• IL-4-increased response of anti bodies

• B7
• -this increases the magnitude of the CD8+ T cell cytotoxic response in tumor bearing hosts resulting in all tumor cells being killed more readily