Biol 224 Lecture 18: T cell function

three major types of t lymphocytes

1. cytotoxic t cells

2. helper t cells

3. regulatory/supressor t cells

Cytotoxic T cells (Tc)

cell mediated immune response, attack abnormal body cell (CD8 markers)

Helper T cells (Th)

activate B cells and stimulate division of other T cells, attack foreign cells and antigens

Regulatory (Supressor) T cells 

Control or moderate immune response of T and B lymphocytes 

Helps against autoimmune disorders 

What is the role of helper T cells in HIV?

Helper T cells activate B lymphocytes which makes antibodies

If helper T cells aren’t activating B lymphocytes antibodies cannot be made, helper T cells also help other t cells multiply which means that there will be low count of cytotoxic t cells as well. Someone with HIV has low counts of helper t which leads to lack of other lymphocytes usually they end up dying from something small and random because their immune system is so weak

Inactive Tc cells

many inactive Tc cells specific for many different antigens present in blood and lymphoid tissues waiting for activation 

How are Tc cells activated?

By binding to class 1 MHC (antigen complex on abnormal cell)

The CD8 marker responds to the Class 1 MHC protein

activation of Tc cells initiates cell mediated immune response against cells with that specific antigen.

Activated Tc cells undergo rapid cell division to produce?

Active Tc cells and Memory Tc Cells

Active Tc Cells

seek out and destroy abnormal cells by releasing destructive chemicals 

Memory Tc Cells

Inactive Tc cells

function during a subsequent exposure to the sam antigen (immunity) 

What are the steps of Tc Cell activation? 

Draw Tc activation and what it does

What are some ways that an active Tc cell can destroy the target cell?

Release perforin to destroy target cells plasma membrane 

Release cytokines and activate genes in target cell to trigger apoptosis

Secrete poisonous lymphotoxin 

How are helper T cells activated?

By binding to Class 2 MHC proteins

These have CD4 markers that respond to MHC 2 proteins 

What does the activation of helper T cells stimulate?

Cell division and to produce active Th cells and memory Th cells

release cytokines that activate b cells and stimulate Tc cells