Download MBBS Physiology Presentations 55 Hematology Immunity 2 Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) 1st Year, 2nd Year, 3rd Year and Final year Physiology 55 Hematology Immunity 2 PPT-Powerpoint Presentations and lecture notes


Immune system-Acquired/Adaptive immunity

Learning Objectives

? To understand about acquired or adaptive immunity

? Steps of humoral immune response

? Steps of cellular immune response

? Cytokines

? Unwanted effects of immune system

? AIDS


Immune system

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Acquired/Adaptive/Specific Immunity

Adaptive immunity is body's

ability to eradicate possibly

harmful foreign materials or

abnormal cells by developing

specific immune response

against a particular antigen.


Acquired/Adaptive/Specific Immunity

Acquired immunity has two components: humoral immunity and cellular immunity.

Humoral immunity is mediated by B Lymphocytes-

Cellular immunity is mediated by T lymphocytes-

MHC Antigens: Major Histocompatibility Complex /

HLA Ag (Human Leukocytes Associated Ag)

These were first identified on the membrane of human leukocytes for the first time.

These glycoproteins are encoded by Histocompatibility Gene on short arm of chromosome 6

These are the self antigens, which are very specific to a person and present on the surface

membrane of all the nucleated cells of body EXCEPT RBCs.


Self to Nonself recognition- Second level caution

MHC Antigens ? 2 Types

MHC Class I MHC Class II

Expressed on almost all cells Expressed mainly on specialized APCs

CD molecule

T-helper cells express CD4 which, facilitates the

binding of MHC-II to the helper T cells receptors.

Cytotoxic T-cells express the molecule CD8 with the

T-cell receptor (TCR). CD8 facilitates the binding of

MHC-I to the T cell receptors


Antigens

Antigen: Elicits a specific immune response in a host.

Epitope: antigenic

Haptens - low molecular weight molecules that are not antigenic but when covalently bound to a

large protein called a `carrier protein' forming Hapten-Carrier Conjugate and become antigenic.

Humoral & Cellular Immunity

Humoral Immunity

It is a `B cells' generated - antibody mediated immune response especially

effective against bacterial antigens.

Cellular Immunity

It is a `T cells' mediated immune response especially effective against

intracellular organisms like viruses, parasites, fungi and others like cancer cells

and transplant cells (few bacterial infection like tubercular bacilli).


Events between entry of ag, its processing and presentation by antigen

presenting cells (Macrophages/B cells) to helper T cells.

Ingestion of Ag

Enzymatic degradation of Ag

Presentation of theses processed Ag

(epitopes)

in association with MHC II to Helper T

cells (TH2) or CD4 cells.

(TH2)



1)TCR are surrounded by Adhesion protein to clomplementary proteins of APC12) Processed Ag to TCR MHCII ?Immunogenic synapse.

Humoral Immunity

Clones of B cells recognize antigens (Clonal

Selection) through the TH2, Gets activated by

the released cytokines

Differentiate into plasma cells and memory

cellsThe immunoglobulins are secreted


Humoral Immunity ? Antibody- Basic Structure

? 2 identical heavy chains
? 2 identical light chains

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? Each heavy chain ? has a constant and

a variable region and each light chain

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has a constant and a variable region.

? Fab ? fragment antigen binding site,
? Fc- Fragment complement and some

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immune cell binding site.

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Humoral Immunity - Effector Phase-Antibodies


Humoral Immunity - Effector Phase-Antibodies-Mechanism of Action

Antibodies released into

the blood stream will

bind to the antigens

that they are specific for.

Humoral Immunity - Effector Phase-Antibodies-Mechanism of Action


Humoral Immunity ? Action of B-Memory Cells

Self Assessment

Humoral immunity is mediated by .................. lymphocytes.

Cellular immunity is mediated by .............. .... lymphocytes.

..................... fragment of antibody is antigen binding site.

........................fragment of antibody is complement and some immune cel binding site.

Presentation of theses processed Ag occurs in association with ............................to Helper T cells.


Thank you

This post was last modified on 08 April 2022