Responses to Antigens

Август 24, 2022

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Responses to Antigens

Содержание

2. Antigen-Any foreign particle Immunogen-Antigen which can provoke immune system Minimum molecular weight of an antigen to
3. Major Histocompatibility Complex/MHC Gene for MHC is located on chromosome no:6 which code for cell surface
4. Antigen presenting cell-these cell captures and process the antigen. macrophage B-lymphocyte Dendritic cell also act as
7. Most abundant 80%
8. Antigen presenting cell Macrophages,B-lymphocytes Dendritic cell Antigen/pathogen Enters the body Captures and process antigen/pathogen Represent to
9. Antibody mediated immunity/Humoral immunity/B-lymphocyte response
10. Cell mediated immunity/T-lymphocyte response
12. AIDS (Acquired Immunodeficiency Syndrome) Caused by HIV(Retrovirus). First case was observed in USA in 1981. HIV
13. shuffling of nucleotides
15. Defence mechanism in response to parasite
17. Protozoa activate quite distinct specific immune responses, which are different from the responses to fungi, bacteria
18. IMMUNE EVASION MECHANISMS OF PROTOZOA: Different protozoa have developed remarkably effective ways of resisting specific immunity:
19. T cells are essential for providing complete protection against T. gondii, which is confirmed by the
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Antigen-Any foreign particle Immunogen-Antigen which can provoke immune system Minimum molecular weight

of an antigen to behave as immunogen should be 750Da. Hapten- Antigen of lower molecular weight.

Epitoke-Antigenic determining site of antigen.
site of antigen to which antibody binds

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Major Histocompatibility Complex/MHC
Gene for MHC is located on chromosome no:6
which

code for cell surface protein essential for the acquired immune system

Types

MHC Class l

MHC Class ll

Works in association with
killer T-lymphocytes(CD-8 receptor)

Works in association with
Helper T-lymphocytes (CD-4 Receptor)

Tissue typing: Matching of MHC during tissue/organ transplantation

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Antigen presenting cell-these cell captures and process the antigen.
macrophage
B-lymphocyte
Dendritic cell also

act as antigen presenting cell

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Most abundant
80%

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Antigen presenting cell
Macrophages,B-lymphocytes
Dendritic cell
Antigen/pathogen
Enters the body
Captures and process antigen/pathogen
Represent

Helper T-lymphocytes

interlukins

Killer T-lymphocytes
clone

interleukins

kinins

B-lymphocytes
clone

Reach to

Site of antigen/pathogen to kill it

Plasma cell

Memory cell

DNA rearrangement

Transformed to

Secrete antibody
@2000/sec

Reach to

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Antibody mediated immunity/Humoral immunity/B-lymphocyte response

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Cell mediated immunity/T-lymphocyte response

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AIDS (Acquired Immunodeficiency Syndrome)
Caused by HIV(Retrovirus).
First case was observed in

USA in 1981.

HIV mainly attacks macrophages and Helper T-Lymphocytes.

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shuffling of nucleotides

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Defence mechanism in response to parasite

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Protozoa activate quite distinct specific immune responses, which are different from

the responses to fungi, bacteria and viruses. Protozoa may be phagocytized by macrophages, but many are resistant to phagocytic killing and may even replicate within macrophages. T. brucei gambiense is the best example of protozoa which can induce humoral immune response because of its extra-cellular location. In Leishmania sp. infections, cellular defense mechanisms depend upon CD4+ T-lymphocytes and activate macrophages as effector cells that are regulated by cytokines of Th1 subset. Plasmodium sp. is a protozoa which show the diversity of defence mechanisms which can be cellular or humoral, depending on Ag and protozoa's location.

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IMMUNE EVASION MECHANISMS OF PROTOZOA:
Different protozoa have developed remarkably effective ways

of resisting specific immunity:
a)anatomic sequestration is commonly observed with protozoa Plasmodium and T. gondii;
b) some protozoa can become resistant to immune effector mechanisms: Trypanosoma, Leishmania and T. gondii;
c) some protozoa have developed effective mechanisms for varying their surface antigens: Plasmodium and Trypanosoma;
d) some protozoa shed their antigen coats, either spontaneously or after binding with specific antibodies: E. histolytica;
e) some protozoa alter host immune response by nonspecific and generalized immunosuppression (abnormalities in cytokine production, deficient T cell activation): Trypanosoma, Leishmania, Toxoplasma, Entamoeba.

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T cells are essential for providing complete protection against T. gondii, which

is confirmed by the finding that mice deficient in T cells are highly susceptible and die as a result of uncontrollable proliferation of the parasite in various organs, including the brain .Both CD8+ and CD4+ T cells are important for controlling T. gondii infection, and IFN-γ production by these cells is critical for protection.

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Responses to Antigens

Содержание

Antigen-Any foreign particle Immunogen-Antigen which can provoke immune system Minimum molecular weight

Major Histocompatibility Complex/MHCGene for MHC is located on chromosome no:6 which

Antigen presenting cell-these cell captures and process the antigen.macrophageB-lymphocyteDendritic cell also

Most abundant80%

Antigen presenting cellMacrophages,B-lymphocytesDendritic cell Antigen/pathogen Enters the bodyCaptures and process antigen/pathogenRepresent