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IMMUNE SYSTEM ORGANS & CELLS

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I – STEM OR MOTHER CELLS:

  • It’s the place of the origin (Generation of lymphocytes)
  • *found in the fetal liver during embryonal life.
  • *then after birth → from bone marrow.

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�II- PRIMARY LYMPHOID ORGANS : (CENTRAL LYMPHOID ORGAN)

  • Function …

*maturation

*education of the cellslymphocyte

*differentiation

  • Where the cells enter to grow, proliferate, mature, differentiate & transformed into the secondary lymphoid organ.

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THESE ORGANS ARE …

  • Thymus → for T-lymphocytes.
  • Bursa equivalent (In mammals), bursa fabracius (In birds).
  • Bursa equivalent (bone marrow) in mammals & payer patches in cattle.

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THYMUS GLAND 1ST

  • It is bi-lobe gland present on both sides in the esophagus in the entrance of esophagus cavity.
  • In birds →it is 14 lobes
  • It found from birth & continue to increase in size to full size at puberty, then decrease in size.
  • The thymus consist of cortex & medulla.
  • There is thymus barrier between the blood and the T cell unable to react with antigen.
  • T- lymphocyte → called T cell because it’s maturation occurin thymus.

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IN THIS THYMUS:

  • The T cell maturation.
  • education (Carry receptor called CD4 & CD8)
  • Differentiation.

T cytotoxic & T suppressor → carry CD8 

T helper → carry CD4

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2ND BURSA OF FABRICIUS

  • Sac of lymphoid tissue present on cloaca present in birds.
  • Responsible for maturation, education & differentiation of B-lymphocytes

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3RD BURSA EQUIVALENT

  • Group of tissues differ from mammals to another.
  • In human, rodents → bone marrow.
  • In cattle → payers patches

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III-SECONDARY LYMPHOID ORGANS:(PERIPHERAL I.O)..

  • Spleen, lymph nodes, tonsils, lymphoid organ (MALT).

MALT→ mucosal associated lymphoid tissue.

  1. Spleen:
    • Consist of white pulb & red pulb.
    • For B cell in perarteriolosheath
    • For T-Cell in white follicle.
  2. Lymph node:

It is consist of : cortex → housing of B-cell

    • Paracortical area → housing T-Cell.
    • Medulla → for another immune cells.
  • Tonsils
  • Malt
    • Aggregates of lymphoid organ. e.g. BALT → baronchial associated lymphatic tissue.
    • MALT → mucosal associated lymphatic tissue.
    • GALT → gut associated lymphatic tissue.

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1ry lymphoid

2ry lymphoid

Other name

Central L.T

Peripheral L.T

Function

Maturation, education, differentiation

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Size

Increase to size ↑ in to full size puberty

The small size on life

Removal

After the immunity

Not affect the puberty

Reaction to antigen

Can’t react with Ag

React with Antigen

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CELL OF IMMUNE SYSTEM

1- Lymphocytes

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B cells

T cells

Origin

B.M, liver of fetus

B.M., liver of fetus

Maturation education

Bursa of fabricius bursa equivalent (B.M., players patches)

Thymus

Storage

Spleen, (Periaertiolar tonsils, cortex) lymph node, MALT.

Spleen (white follicle), tonsils (Paracortical area) L.node, MALT

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CONTINUE….

Types

One

1 type

Th→ T helper, help both humeral and cell mediated immunity (Carry CD4)

Tc → T cytotoxic

Ts → T suppress of immune system after complete Ag destructiare.

Cells products (Secretions)

Bcel differentiate to plasma cell & memory cells.

Plasma cell: secret Antibody

Active Tc release certain enzymes called lymphokine.

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CONTINUE….

Lymphocytes transformation

Yes to plasma cell

Yes to small lymphocytes

Life spane

Short

Long

Receptor

  1. For Ag

BCR

TCR

2. E-rosette formation (receptor to sheep RBC)

No

Yes

3. C3b for complement

Yes

No

4. Carry MHC

MHCI &MHCII because it is Apc

MHCI

5. Other receptor

CD19, CD21

CD3

Th → CD4

Tc & Ts → CD8

CD2 & CD 58

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CELLS THAT LINK IN INNATE & ADAPTIVE IMMUNITY (APC)..

Antigen Presenting Cells:

A) Dendritic cell:

  • It is cell found in epithelial tissue.
  • It is APC & act also as phagocytic cell as m.ø.

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What is APC doing?

  • APC → Carry to Ag on MHCII, this antigen is exogenous Ag- & present it to Th.
  • T helper carry CD4 for MHCII or carry Ag direct to B cells.
  • N B APC → carry the antigen after engulfment, fragmentation to different epitopes.
  • Then epitope exposed on surfaces of APC with MHCII.

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B) Macrophage: as (A)

C) B cells:

  • Act as APC in the 2ry immune response
  • Can be activated directly by exogenous antigen but fully activated by T-helper cell which secret factors → help B-cell to be fully activated.

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RECEPTORS OR MARKERS OF T & B CELL

1) Ag binding receptors → BCR, TCR

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BCR (B cell receptor)

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  • 2 class of immunoglobulin (IgM and IgD)
  • There are 200,000- 500,000
  • Bivalent
  • Specified

TCR (T cell receptor)

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  • 2 polypeptide (α, β)
  • 100,000 copy
  • Is less
  • Not specified

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2) OTHER RECEPTOR ON T CELL

  • CD2 & CD58 → Bind m.ø.
  • CD3 → To amplify signals.
  • CD4 on Th → for MHCII.
  • CD8 on Tc & Ts → for MHCI.

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3) MAJOR HISTO-COMPATIBILITY COMPLEX

  • Group of surface receptor.
  • MHCI: On an nucleated cells, carry endogenous antigenous for T cytotoxic & T suppressor.
  • MHCII: on APC (m.ø. B cells & dendritic cells)
    • Carry exogenous Ag.
    • To T helper and B cells

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4) RECEPTOR FOR REGULATOR THE FUNCTION OF T & B CELLS

  • For complement
  • For cytokine
  • For antibody

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5) RECEPTOR FOR UNKNOWN FUNCTION.

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THANK YOU