Cancer is a state which involves an abnormal increase in the number of cells, with a potentiality to invade or spread to other parts of the body and destroy their function. Every individual is born with an immune system that acts as a security checkpoint. The immune system does possess B and T lymphocytes, B -cells act as the military intelligence and T -cells act as soldiers it also possesses some receptors that scan normal cells and abnormal cells like a virus and some other cells. abnormal cells are detected and removed by the T -cells, but in some conditions, T-cells fail to detect and eliminate cancer cells. This is because of higher mutations in cancer cells leads to a development of some of the receptors like PD -L1 which acts as the signal jammer of the T -cell. This leads to failure in the work of T -cells against the cancer cells

In normal conditions, B-cells are like the body’s military intelligence system, search targets and sending defences to lock onto them. T cells are like the soldiers, destroying the foreign agents that the intelligence system has identified. T-cells get attached to  the  target cell, cytotoxic   T  cells do possess TCR(T-cell receptor), CD8 and some receptors   and   target   cells   do   possess   MHC molecule ,when T-cell attaches to  abnormal cells they do release some toxic materials like perforins and some others materials perforins are the proteins one  of  the  main  cytolytic  proteins  of  cytolytic granules, and it is known to be a key effectors molecule for T-cell and natural killer-cell-mediated cytolysis because of this granules lead to pore in target cells and finally it leads to the dying of the target cells and cytotoxic T -cell gets released from the target cells.

  Mechanism of T-cell how it attacks the abnormal cell

Whereas in   cancer cells   which are   highly mutated in that condition T -cell does not show any of its action this is because T -cells possess PD-1 which acts as the signalling system, cancer cells possess PD-L1 molecule which acts as the signal jammer of the T-cell. and B7.1 or CD 80  that ac ts as the alarm when something is wrong which helps in   the   activation  of   T-cells   by   inhibiting  the stimulus of T-cell finally, that leads to the escape of the tumor cells from the immune checkpoints, cytotoxic  T-lymphocyte-associated protein 4(CTLA-4) receptor expressed on activated T -cells which function as an inhibitory receptor which inhibits   T-cell   activation   not   only   this   two receptors  so  many  receptors  are  present  which makes cancer cells to  live freely and T – cells are gets inhibited their activity. B y triggering some of these   sites   may   leads   to   the   development  of treatment   for   many   cancer   diseases   like   lung disease and some other disease.

PROGRAMMED CELL DEATH

PD-1 (Programmed death- 1) is expressed on monocytes, T cells, B cells, dendritic cells,  natural killer cells and many tumour-infiltrating lymphocytes (TIL).PD-1 is expressed in regulatory T cells and able to facilitate the proliferation of regulatory T cells and restrain immune response³, PD-L1 (Programmed death-ligand 1)is expressed in various cancers cells , especially in  Non-small cell lung cancer (NSCLC), gastric cancer, melanoma, hepatocellular, renal cell carcinoma as well as various leukemias and so on⁴.PD-L1 is induced by multiple proinflammatory molecules like  TNF-α, LPS, Granulocyte-macrophage colony-stimulating factor and Vascular endothelial growth factor, as well as the cytokines IL-4and IL-10, with IFN-γ being the most potent inducer⁵. PD-L1 is regulated by oncogenes( a gene that has the power to cause cancer), also known as the inherent immune resistance in cells. And drugs against this are ANTI-PD-1 and ANTI-PD-L1  are effective.

Research in immunotherapy gives a new wide space for the treatment of various cancer disease like myeloma, NSCLC and etc, when we compare this immunotherapy with that of radiotherapy,chemotherapy this gives a wide range of results with relatively safer, less toxic, effective and etc conditions  anti-CTLA-4 monoclonal antibody therapy has shown promise in a number of cancers, particularly melanoma and also antiPD-1/PD-L1 this therapy has shown an effect on patient with the NSCLC have been benefited.With the elaborated studies on a biological marker and combined treatment in the PD-1/PD-L1 or CTLA-4 will make a new sense in development of immunity against cancer diseases and which make a new revolution in the treatment of cancer disease.