The Immune reaction (also immune response) describes the reaction of the immune system to foreign cells or substances. These include allergens, bacteria, parasites, fungi, tumor cells, viruses (see picture) and, last but not least, toxic substances. Defense cells in the service of the immune system recognize on the basis of the surface structure of the proteins, whether it is an endogenous or foreign body cell. If a cell is recognized as foreign to the body, different defense processes take place in parallel:
Here, a first distinction between the innate immune response (represented in the genome) and the acquired immune response (learned from the immune system) can be done. Based on this, these components can still be classified in the cellular or humoral immune reaction. The cellular immune response includes all, by cells (!) Coordinated, defense processes. In contrast, the humoral defense (lat. Umor = fluid) works by means of special proteins (!). The following table lists the individual components according to their affiliation.
Table: Overview of possible immune responses
|Humoral immune response||Cellular immune response|
| Specific immune defense|
(Acquired immune defense)
| Unspecific immune defense|
(Innate Immune System)