Final answer:
Cytotoxic T cells specifically target and destroy cells infected by viruses without harming uninfected cells due to the presence of unique receptors that recognize infected cells. Memory T cells provide lasting immunity against previously encountered viruses. This specificity allows for an effective immune response while protecting healthy tissue.
Step-by-step explanation:
T-cells, specifically cytotoxic T cells, play a crucial role in our body's defense against viruses without damaging our own cells. These T cells recognize and destroy cells infected by viruses while leaving healthy cells mostly unharmed, thanks to the presence of specific receptors that can distinguish infected cells from normal ones.
When a virus infects a cell, the cell presents viral peptides through its Major Histocompatibility Complex (MHC) class I molecules. Cytotoxic T cells recognize these MHC-viral peptide complexes through their T cell receptors (TCR), which triggers their activation. Once activated, cytotoxic T cells release various substances that lead to the destruction of the infected cell, thus preventing the virus from replicating and spreading.
The specificity of this system is key to understanding why T cells do not generally harm uninfected cells - the receptors on the T cells are finely tuned to recognize the specific markers of infection. Moreover, memory T cells remain in the body after the initial immune response. These cells offer rapid and effective protection in the event the body re-encounters the same virus.
It is this carefully orchestrated response that allows the immune system to target only those cells that have been compromised by viral infection, sparing the rest of the body's cells. This targeted defense is essential to maintaining healthy tissues while effectively fighting off viral pathogens.