Immune response ppt

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Immune response

Dr Vijay Marakala MDvkunder637@gmail.com

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THE IMMUNE SYSTEM

We are constantly exposed to an incredible diversity of bacteria, viruses, and parasites

How does the immune system protect us?

The key isour ability to produce more than 108 distinct antibodies and more than 1012 T-cell receptors

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The immune system has 2 arms

Innate immunity

Adaptive immunity

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The Immune System is the Third Line of Defense Against Infection

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Immune response

• The specific reactivity induced in a host by an antigenic stimulus

2 TYPES:

1. Humoral (AMI)

2. Cellular (CMI)

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LYMPHOCYTES INVOLVED IN THE IMMUNE RESPONSE

B lymphocytes T lymphocytes

Mainly derived from bone marrow

T lymphocytes are of thymic origin

HUMORAL IMMUNITY CELLMEDIATED IMMUNITY

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• The production of antibodies consists of 3 steps

Humoral Immune response(AMI)

Entry Processing Secretion

Afferent limb Central limb Efferent limb

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Antibody production follows a characteristic pattern

Lag phase Log phase Plateau or steady state

Phase of decline

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ANTIBODY RESPONSE AFTER EXPOSURE TO ANTIGEN

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Fate of antigen in tissues

Antigen Introduced I.V SPLEEN

LIVER BM

KIDNEY LUNGS

Broken down by RE cells

70-80% Excreted in the urineEliminated within 1 or 2 days

Introduced S.C

Draining lymph nodes

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Fate of antigen in tissues

• Antigens are removed from circulation in 2 phases

Non-immune phase Phase of immune elimination

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PRODUCTION OF ANTIBODIES

• Immune response to an antigen is brought about by 3 type of cells

APC T-cells B-cells

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ANTIGEN-PRESENTING CELLSCapture

Display

Signal

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ANTIGEN-PRESENTING CELLS

Macrophages

Dendritic cells

B lymphocytes

Follicular dendritic cells

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Major Histocompatibility Complex

• The task of displaying cell-associated antigens for recognition by T cells is performed by specialized proteins that are encoded by genes in a locus called the MHC

2 TYPES

Class I MHC

Class II MHC

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Major Histocompatibility Complex

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Major Histocompatibility Complex

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Lymphocytes

B - Lymphocytes HUMORAL IMMUNITY

T - Lymphocytes CELL MEDIATED IMMUNITY

Helper T cellsCytotoxic T cellsNK cells

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Lymphocytes

• Provides 2 defining characteristics of the adaptive immune response,

1.Specificity

2. Memor

y

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T Cells Only Recognize Antigen Associated with MHC Molecules on Cell Surfaces

T cell recognize with the help of T cell receptor

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T CELL RECEPTOR

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Central Role of Helper T Cells

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CYTOTOXIC T CELLS LYSE INFECTED CELLS

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Humoral Response to Antigens

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Factors influencing antibody production

Genetic Age Nutrition

Route of administration

Size & number of doses Multiple antigens

Adjuvants Immunosuppressive drugs Effect of antibody

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CELLULAR IMMUNE RESPONSE (CMI)

Specific immune response that do not involve antibodies.

Delayed hypersensitivity

Immunity in infections

Transplantation immunity

Immunological surveillance

Autoimmune disease

Scope of CMI

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Induction of CMI

• Antigenic stimulus• Only T-cell dependant antigens lead to CMI• T-cell bears specific receptor on its surface• T cells recognize antigens only when

presented with MHC molecules• Helper T-cells• Cytotoxic T-cells

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CYTOKINES• Biologically active substances released by

activated T lymphocytes were called LYMPHOKINES

• Similar substance produced by Monocytes Macrophages

MONOKINES

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CYTOKINES•MIF• MAF• MCF

Affecting macrophages

•BF/MF• TGF•BGF

Affecting lymphocytes

•CF•CSF

Affecting granulocytes

•LT•IFN•TNF

Affecting cultured cells

•SRF•TFOthers

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CYTOKINES - CLASSIFICATION•IL-1•IL-2•IL-3…13

Interleukins

•GM-CSF•G-CSF•M-CSF

Colony stimulating factors

•TNF-α•TNF-β

Tumour necrosis factors

•IFN-α•IFN-β•IFN-γ

Interferons

•TGF-β•LIFOthers

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Cytokines • Peptide mediators or intracellular messengers

which regulate immunological, inflammatory and reparative host responses

• They are potent hormone like substances

• Produced by lymphocytes, macrophages, platelets & fibroblasts

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Cytokines

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• Source: Macrophages & other cells• IL-1α and IL-1β• Functions: Proliferation & differentiation of T, B and other

cells Pyrogenic Induce acute phase proteins Bone marrow cell proliferation

Interleukin-1 (LAF)

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• Source: T-cells• Powerful modulator of the immune response• Functions: Promote growth and differentiation of T and B

cells Cytotoxicity of T and NK cells Secretions of other lymphokines

Interleukin-2[TCGF]

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Interleukin-2[TCGF]

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Other interleukins

Interleukin-3 (multi-CSF) Growth factor for bone marrow stem cells

Stimulates hematopoiesis

Interleukin-4 (BCGF-I) Differentiation and proliferation of B and T cells

Enhances the activity of cytotoxic T cells

Activates mast cells

Interleukin-5 (BCGF-II) Proliferation of activated B cells

Induces maturation of eosinophils

Interleukin-6 Induces immunoglobulin synthesis by activated B cells

Induces formation of IL2 receptors on T cells

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• Stimulates the growth & differentiation of pleuripotent stem cells in the bone marrow

• Responsible for adjusting the rate of production of blood cells

• Treating hematopoietic dysfunctions in infections & malignancies

Colony stimulating factors

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• Induce hemorrhagic necrosis in certain tumours

• 2 types: TNFα and TNFβ• Cachectin is TNFα

Tumour necrosis factors

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• Originally identified as antiviral agentsα-Produced by leucocytesβ-Produced by fibroblastsγ-Produced by T-cells• Functions: Macrophage activation Antitumour activity

Interferons

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Kuby IMMUNOLOGY

Fifth Edition

REFE

REN

CES