Innate and adaptive immune system

February 14, 2017

what type of virus, protein, bacteria, fungus, etc. is trying to get inside but knows that it looks shady and needs to be denied the entrance in the organism.

Innate immune system is constituted by the first line of defenses –barriers-, for example the stomach’s acid, and the oil acidity on the skin, the enzymes in the tears, the hair and mucus in the nose etc. Natural barriers that don’t allow things inside the body, but once they get in the innate immune system has the second line of defense, that tries to eliminate any foreign organism that find their way into the body by lysing and provoking an inflammatory response. This is the second line of defense which is constituted by macrophages and neutrophiles, all of them leukocytes or white blood cells.

The adaptive immune system which specifically fights the invader recognizes the type of infection that it is being challenged with and mount a specific response to fight it.

The main intervenients in this response are the lymphocytes, another type of white blood cell, that although they have different roles they interact with each other. Lymphocytes can be divided into B lymphocytes, also known as B-cells, and T lymphocytes, also known as T-cells. B-cells are produced and matured in the bone marrow while T-cells are produced in the bone marrow but mature and became active in the thymus. B-cells are responsible for the humoral response and T-cells are responsible for the cell mediated response and play a crucial role in amplifying and activating the B-cells.

The humoral response is active while virus and bacteria are floating around and has still not infected the host cells; they get recognized by the immune system and eliminated before they can be a threat. The cell mediated response come into action when host cells became infected and are helping the pathogen to replicate. There is a necessity then to kill the infection even if to do would mean killing the host cell.