Immune Responses Against Tumors and Transplants PDF

Immunogenic responses against Tumors Immunotherapies, vaccines, and adoptive-cell therapy can help turn the immune system against tumors. Checkpoint blocking immunotherapy (CBI) is a strategy that activates anti-tumor immunity by blocking tumor T cell suppression The immune system's response to tum...

Immunogenic responses against Tumors Immunotherapies, vaccines, and adoptive-cell therapy can help turn the immune system against tumors. Checkpoint blocking immunotherapy (CBI) is a strategy that activates anti-tumor immunity by blocking tumor T cell suppression The immune system's response to tumors is complex and involves both innate and adaptive immunity: Innate immunity The initial response to tumors, which is general and non- specific. It's mediated by cells like dendritic cells, macrophages, natural killer (NK) cells, and natural killer T (NKT) cells. Adaptive immunity This response is largely mediated by cytotoxic T lymphocytes (CTLs), which recognize and destroy tumor cells. CD4+ TH lymphocytes also help by secreting cytokines that stimulate CTLs. The immune system can act against tumors in several ways, including: Immunoediting: The immune system recognizes and rejects malignant cells, which inhibits tumour growth. Presenting tumour antigens: Immune cells absorb and present tumor antigens on their surface. Releasing cytokines: Immune cells release cytokines that activate and recruit other immune cell. Directly killing tumor cells: CTLs kill tumor cells by cytolysis. Cancer and treatments may weaken immunity: Cancer can weaken the immune system by spreading into the bone marrow. Open a glossary item The bone marrow makes blood cells that help to fight infection. This happens most often in leukaemia or lymphoma, but it can happen with other cancers too. The cancer can stop the bone marrow from making so many blood cells. Certain cancer treatments can temporarily weaken the immune system. This is because they can cause a drop in the number of white blood cells made in the bone marrow. Cancer treatments that are more likely to weaken the immune system are:  chemotherapy  targeted cancer drugs  radiotherapy  high dose of steroidS. The immune system can help to fight cancer Some cells of the immune system can recognise cancer cells as abnormal and kill them. But this may not be enough to get rid of a cancer altogether. Some treatments aim to use the immune system to fight cancer. There are 2 main parts of the immune system: the protection we have from birth (in built immune protection) the protection we develop after having certain diseases (acquired immunity). In Built Immune Responses This is also called innate immunity. These mechanisms are always ready and prepared to defend the body from infection. They can act immediately (or very quickly). This in-built protection comes from: A barrier formed by the skin around the body the inner linings of the gut and lungs, which produce mucus and trap invading bacteria hairs that move the mucus and trapped bacteria out of the lungs stomach acid, which kills bacteria helpful bacteria growing in the bowel, which prevent other bacteria from taking over urine flow, which flushes bacteria out of the bladder and urethra white blood cells called neutrophils, which can find and kill bacteria Different things can overcome and damage these natural protection mechanisms. For example: something may break the skin barrier, such as having a drip in your arm or a wound from surgery a catheter into your bladder can become a route for bacteria to get inside the bladder and cause infection anti acid medicines for heartburn may neutralise the stomach acid that kills bacteria Certain cancer treatments can also overcome these protection mechanisms. Chemotherapy can temporarily reduce the number of neutrophils in the body, making it harder for you to fight infections. Radiotherapy to the lung can damage the hairs and mucus producing cells that help to remove bacteria. Neutrophils Neutrophils are a type of white blood cell that are very important for fighting infection. They can: move to areas of infection in the body stick to the invading bacteria, viruses or fungi swallow up the bacteria, viruses or fungi and kill them with chemicals When you don't have enough neutrophils in your blood, doctors may say that you are neutropaenic. Chemotherapy, targeted cancer drugs and some radiotherapy treatments can lower the number of neutrophils in the blood. So you might get more bacterial or fungal infections after these treatments It is important for you to know the following when having cancer treatment: Infections can become serious very quickly in people with low neutrophil counts antibiotics could save your life so if you get a fever or feel ill phone your advice line or go to hospital straight away you might need to take antibiotics to help prevent severe infection if your blood counts are low. It is more usual to become ill from bugs you carry around with you than from catching someone else's. This means that you shouldn't have to avoid contact with your family, friends or children after treatment. You can ask your doctor or nurse what precautions you should take against infection.