Uploaded April 2019 | Updated September 2026, 2 weeks ago
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This video is about T-Lymphocyte development and function
Content:
0:00 Introduction
0:06 T-Cell Development
3:43 How CD4+ (T Helper Cells) is Activated
6:48 How CD8+ (T Cytotoxic Cells) is Activated
10:01 Th17 (Activation/Function)
14:46 T-Cell Tolerance (T-Regulatory Cells)
17:11 Time Needed for Immunological Memory
βββββββββββββββββββββ-
All information in my immunology videos are from:
- Book: Immunology, Eighth Edition by David Male, Jonathan Brostoff, David Roth and Ivan Roitt
- Additional research in PubMed
- University lecture materials
ββββββββββββββββββββββ
Development of T-lymphocytes:
1. In red bone marrow as Multipotent lymphoid stem cell
2. Goes to the Thymus to develop further there
Thymus:
Grow to max around puberty, and then gradually become replaced by fat tissue
Stages of t-cell development in thymus:
1. Double negative stage: Check if the cell lack CD4/CD8
2. Double positive stage: check if they express cd4/cd8
3. Positive Selection: Check if recognize self MHC
4. Negative Selection: Check if recognize self antigen
5. Single positive selection: Become either CD4+ or CD8+ T-lymphocyte
6. Then goes to the secondary lymphoid organs
They undergo apoptosis if fail in one of the stages
CD4+ activation - T helper Cells
3 activation signal needed to activate naive T cells
- 1st activation signal: MHC - TCR (Receptor + CD4 + CD3)
- 2nd activation signal: B7 - CD28
- 3rd activation signal: Interleukin 4 (IL4) give Th2, Interleukin 12 (IL12) give Th1 - Then it secretes IL2 (Autocrine) to help itself grow
Th2 cell release:
- IL10 - supresses Th1 response
- IL4 IL5 IL6 - Stimulate B-cell for IgG/IgE/IgA synthesis
Th1 cell (inflammatory t helper cell) release:
- Interferon gamma (IFN-g) - Activate amcrophages, IgG synthesis and decreases Th2 response
- IL2 - Help growth of B- and T-cells
CD8+ activation - Cytotoxic T-cell:
- When Virus infects a normal cell: become Non-professional APC and usually gets phagocytosed by APC - MHCII/I
- When virus infects an APC - present on MHC II/I
1. T-Cytototoxic cell binds to MHC I through TCR (3 activation signals needed)
2. Th0 binds to MHCII and becomes Th1 which help Tcyt further differentiate by releasing IFNg and IL-2
Activated T-cyt undergoes clonal expansion and expresses Fas-L to kill infected cells who express Fas by releasing Perforin (make hole on surface) and Granzyme B (fragments DNA)
Activated Th1: Activated macrophage by CD40L/CD40 and IFN-g which will phagocyte the remaining parts of the virus/cell
Th17:
Good against infections by Fungi
- Severe fungal infection is on immunesurpressed people.
How to get Th17:
- Macrophage phagocytes fungi
- presents 3 activation signals on naive T helper cell (Th0)
- Macrophage release IL1, IL6, IL23 and Transforming growth factor beta (TGF-a) which makes Th0 into Th17
Activated Th17 release:
- IL17 - recruite neutrophiles. Neutrophils will promote inflammation by releasing granuoles, lysozymes and reactive oxygen species
- IL22 and IL17 will stimulate epitheliual cells to produce antimicrobial proteins into releasing defensins
Activates Th1 (by IL12):
- Activate macrophages by CD40L/CD40 and IFNg and release pro inflammatory cytokines (IL1, IL6 and TNF-a)
T cell tolerance:
Eliminating cells that react to self antigens
Central Tolerance in Thymus:
Kill self reactive T cells
Peripheral Tolerance (Extrathymus):
Escaped T cells go to secondary lymphoid organs. Inhibited by direct inactivation (clonal deletion) and T-regulatory cell
T-reg release:
- IL35: supresses immune funtion
- IL10: decreases function of Th1
- TGF-b inhibits macrophages
They decrease function of dendritic cells
They can sense amount if IL2 and regulate function based on that.
How many days does it take to gain immunological memory?
- Start as naive
- Clonal expansion until around 7 days
- Give Effector Response
- Decreases until it becomes memory cells. Memory cells decrease slowly at 14 days.
π Website: taimtalksmed.com
π« Help keep this content free: youtube.com/channel/UCEr7pkSXVsHcBLLBcJAGV-Q/join
π¬ Get 10% off anatomy lab models (affiliate link): https://anatomywarehouse.com?aff=34
π² Other Links:
Instagram: instagram.com/taimtalksmed
Discord: discord.com/invite/DENMUpS8ey
This video is about T-Lymphocyte development and function
Content:
0:00 Introduction
0:06 T-Cell Development
3:43 How CD4+ (T Helper Cells) is Activated
6:48 How CD8+ (T Cytotoxic Cells) is Activated
10:01 Th17 (Activation/Function)
14:46 T-Cell Tolerance (T-Regulatory Cells)
17:11 Time Needed for Immunological Memory
βββββββββββββββββββββ-
All information in my immunology videos are from:
- Book: Immunology, Eighth Edition by David Male, Jonathan Brostoff, David Roth and Ivan Roitt
- Additional research in PubMed
- University lecture materials
ββββββββββββββββββββββ
Development of T-lymphocytes:
1. In red bone marrow as Multipotent lymphoid stem cell
2. Goes to the Thymus to develop further there
Thymus:
Grow to max around puberty, and then gradually become replaced by fat tissue
Stages of t-cell development in thymus:
1. Double negative stage: Check if the cell lack CD4/CD8
2. Double positive stage: check if they express cd4/cd8
3. Positive Selection: Check if recognize self MHC
4. Negative Selection: Check if recognize self antigen
5. Single positive selection: Become either CD4+ or CD8+ T-lymphocyte
6. Then goes to the secondary lymphoid organs
They undergo apoptosis if fail in one of the stages
CD4+ activation - T helper Cells
3 activation signal needed to activate naive T cells
- 1st activation signal: MHC - TCR (Receptor + CD4 + CD3)
- 2nd activation signal: B7 - CD28
- 3rd activation signal: Interleukin 4 (IL4) give Th2, Interleukin 12 (IL12) give Th1 - Then it secretes IL2 (Autocrine) to help itself grow
Th2 cell release:
- IL10 - supresses Th1 response
- IL4 IL5 IL6 - Stimulate B-cell for IgG/IgE/IgA synthesis
Th1 cell (inflammatory t helper cell) release:
- Interferon gamma (IFN-g) - Activate amcrophages, IgG synthesis and decreases Th2 response
- IL2 - Help growth of B- and T-cells
CD8+ activation - Cytotoxic T-cell:
- When Virus infects a normal cell: become Non-professional APC and usually gets phagocytosed by APC - MHCII/I
- When virus infects an APC - present on MHC II/I
1. T-Cytototoxic cell binds to MHC I through TCR (3 activation signals needed)
2. Th0 binds to MHCII and becomes Th1 which help Tcyt further differentiate by releasing IFNg and IL-2
Activated T-cyt undergoes clonal expansion and expresses Fas-L to kill infected cells who express Fas by releasing Perforin (make hole on surface) and Granzyme B (fragments DNA)
Activated Th1: Activated macrophage by CD40L/CD40 and IFN-g which will phagocyte the remaining parts of the virus/cell
Th17:
Good against infections by Fungi
- Severe fungal infection is on immunesurpressed people.
How to get Th17:
- Macrophage phagocytes fungi
- presents 3 activation signals on naive T helper cell (Th0)
- Macrophage release IL1, IL6, IL23 and Transforming growth factor beta (TGF-a) which makes Th0 into Th17
Activated Th17 release:
- IL17 - recruite neutrophiles. Neutrophils will promote inflammation by releasing granuoles, lysozymes and reactive oxygen species
- IL22 and IL17 will stimulate epitheliual cells to produce antimicrobial proteins into releasing defensins
Activates Th1 (by IL12):
- Activate macrophages by CD40L/CD40 and IFNg and release pro inflammatory cytokines (IL1, IL6 and TNF-a)
T cell tolerance:
Eliminating cells that react to self antigens
Central Tolerance in Thymus:
Kill self reactive T cells
Peripheral Tolerance (Extrathymus):
Escaped T cells go to secondary lymphoid organs. Inhibited by direct inactivation (clonal deletion) and T-regulatory cell
T-reg release:
- IL35: supresses immune funtion
- IL10: decreases function of Th1
- TGF-b inhibits macrophages
They decrease function of dendritic cells
They can sense amount if IL2 and regulate function based on that.
How many days does it take to gain immunological memory?
- Start as naive
- Clonal expansion until around 7 days
- Give Effector Response
- Decreases until it becomes memory cells. Memory cells decrease slowly at 14 days.
