Summary
Recognition of peptide-MHC with co-stimulation activates T cells through kinase cascades like ZAP-70.
In depth
The TCR binds peptide-MHC with CD4 or CD8 co-receptor; Lck phosphorylates ITAMs of CD3, ZAP-70 is recruited and downstream pathways (NFAT, NF-kB, AP-1) activate. A second signal from CD28-B7 is needed; without it cells become anergic.
Two signals are required: TCR-MHC and co-stimulation. Cytokines provide a third signal for differentiation. Checkpoints (PD-1, CTLA-4) limit activation.
Example: lack of co-stimulation causes anergy and protects from autoimmunity.
Signal 1 is TCR engagement, signal 2 is co-stimulation by CD28, and signal 3 is cytokines that shape differentiation. Downstream pathways, including calcium-NFAT, PKC-NF-kB and Ras-MAPK, drive transcription of IL-2 and proliferation. Inhibitory receptors such as CTLA-4 and PD-1 provide brakes. The immunological synapse is a structured contact between the T cell and presenting cell.
Drugs interfering with this pathway include ciclosporin and tacrolimus (inhibit calcineurin, blocking NFAT), and abatacept (CTLA-4-Ig). Mutations in signalling components cause immunodeficiency, and engineered receptors in CAR-T cells use the same logic.
Frequently asked questions
What is T Cell Receptor Signalling?
Recognition of peptide-MHC with co-stimulation activates T cells through kinase cascades like ZAP-70.
Which area of biology covers T Cell Receptor Signalling, and how advanced is it?
T Cell Receptor Signalling is one of the 52 topics in Immunology & Disease. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Adaptive Immunity, Immunological Tolerance, Immune Checkpoint Therapy.
Why does T Cell Receptor Signalling matter?
The signal strength and context decide whether a T cell activates, becomes tolerant or dies.
Can you give an example of T Cell Receptor Signalling?
CTLA-4 competes for B7 to dampen responses.
What should I learn before T Cell Receptor Signalling?
Work through the Beginner topics in Immunology & Disease first, such as Immune System, Viruses, Innate Immunity, then return to T Cell Receptor Signalling. Advanced topics assume the Intermediate vocabulary.
What topics are related to T Cell Receptor Signalling?
The closest topics to T Cell Receptor Signalling are Adaptive Immunity, Immunological Tolerance, Immune Checkpoint Therapy, Natural Killer Cells. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand T Cell Receptor Signalling?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for T Cell Receptor Signalling. To practise the whole of Immunology & Disease, use the Immunology & Disease quiz.
How is T Cell Receptor Signalling different from Adaptive Immunity?
T Cell Receptor Signalling: Recognition of peptide-MHC with co-stimulation activates T cells through kinase cascades like ZAP-70. Adaptive Immunity: Slower, specific defence involving lymphocytes that remember pathogens. Read both side by side and note what each one explains.
How should I study T Cell Receptor Signalling step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Adaptive Immunity and explain the difference aloud. Finally, take the Immunology & Disease quiz and come back to this page for any question you miss.