3. Activated T cells start to express CTLA-4 on their surface, because CTLA-4 has 100 folder higher affinity to B7, CTLA-4 activation become dominant which inhibit the TCR signaling.
PIRB(paired
immunoglobulin-like receptor
B ) ITIMs recruites SHP1,
which dephosphorylates
various protein-tyrosine
kinases, including SYK and
Bruton's tyrosine kinase
Excessive response lead to endotoxic shock (sepsis): Sepsis(败血 症) is a serious medical condition that is characterized by a wholebody inflammatory state (called a systemic inflammatory response syndrome or SIRS) and the presence of a known or suspected infection. The body may develop this inflammatory response to microbes in the blood, urine, lungs, skin, or other tissues. A lay term for sepsis is blood poisoning.