Adaptive Immunity and Innate Immunity Explanation and Differences

Adaptive Immunity and Innate Immunity Explanation and Differences

Everyday we encounter huge number of bacteria, viruses and other disease causing organisms. However we do not fall ill every day, which is due to our immune system, an army of cells that is always roaming inside our body to attack any pathogens which try to harm our body. The immune system can be broadly divided into two parts innate and adaptive immunity.

Innate immunity or non specific immunity is the bodies first natural defense to any intruder, this system does not care what its killing, its primary goal is to prevent any intruder entering the body and if does enter then the immune system kills the intruder. It does not differentiate between one pathogen and other pathogen.

Skin Defense

The first component of this defensive system is our skin, any organism trying to get into the body is stopped by the skin which is our largest organ which covers us. Secondly there is a mucous lining of all our organs. The sticky, viscous fluid of this lining traps any pathogens trying to get past it. These are the two physical barriers, however we also have chemical barriers such as the lysozyme in the eyes, or the acid in the stomach which can kill pathogens trying to get entry into our body.

The genitourinary tract and other places have their own normal flora or microbial community, these compete with pathogens for space and food and therefore these also act as barriers.

Mast Cells

The next line of defense is inflammation which is done by mast cells, these cells are constantly searching for suspicious objects in the body, when these cells find something then they release a signal in the form of histamine molecules, these alert the body and blood is rushed to the problematic area. Thsi causes inflammation and also brings leukocytes or white blood cells (WBC), which are soldiers in our bodies cellular army. Sometime the intruder may not be a germ, it might be harmless dust. The body still causes a full immune reaction to this intruder, which is how allergic reactions occur.

The leukocytes are VIP´s in our body they have all access pass inside our body except the brain and spinal cord. Leukocytes come in many types, those that belong to the innate immune system are known as Phagocytes, these cells can either petrol your body like neutrophils or they can stay in certain places and wait for their cue.


Neutrophils are the most abundant cells, they patrol the body and therefore get to a breach site very quickly.  These cellular soldiers kills the infectious cell and the die which leads to the pus formation. There are also the big bad wolves or the Macrophages, these cells are like hungry monsters who engulf unwanted pathogens, instead of roaming freely in pour blood they are collected in certain places, these cells can consume 100 pathogens before they die and they also can detect our own cells that have gone rogue such as cancer cells and kill them too.

Beyond that we also have natural killer cells, these cells can efficiently detect when our won cells have gone rogue or are infected with a virus. NKC´s detect a protein produced by normal cells called the Major Histocompatibility Complex or MHC. Basically when a cell is´nt normal it stops producing the protein, the NKCś move around constantly checking our cells for this type of deficiency and when they find an abnormal cell they simply bind to it and release chemicals that will destroy it.

The last cells of our innate system are the Dendritic cells, these are found in places that come in contact with the outside environment such as the nose, lungs etc., they are the link between our innate and adaptive immune systems. They eat a pathogen and carry information about it to our adaptive immune system cells, this information is produced and shared in the form of antigens. Antigens are the traces that pathogens leave around, they are molecules found on the surface on pathogens, that can be detected by our adaptive immune system for recognition.

The dendritic cells pass on the information to our T-cells, however Macrophages can also perform this function

Adaptive immunity and Innate immunity Info graphic | Adaptive immunity vs Innate immunity

Adaptive Immunity and Innate Immunity Explanation and Differences


This system is more efficient as it can differentiate between different types of pathogens, it has two main components T-lymphocytes and  B-lymphocytes. T-cells come into play when an infection is already occurred , thus bringing about the cell-mediated immune response. B-cells join the fight when the pathogens have entered but yet haven´t caused any disease, this is called Humoral Immune Response

Some T-cells take signals from the dendritic cells or the macrophages and are called Helper T-cells, they perform two key tasks

  • Forming effector T-cells, which are basically cells that cycle through the body and call in the cavalry namely the other white blood cells (WBCś)
  • Helper T-cells also form memory T-cells, which keep a record of this antigen for future reference

Some times cells of our body know that they have lost the battle, essentially the effected area or organ has they have become heavily infected with pathogens, so there is no hop[e for them. At this point the immune system brings out the Cytotoxic T-cells. These cells rush over and perform mercy killing for the infected and dying cell.

Furthermore we have the B-cells, they produce chemicals called antibodies, which fit on the antigens of pathogens, just like lock and key fit together. These antibodies crowd around pathogen and act like tags. They signal the macrophages to come and kill the marked pathogen.

B-cells also produce memory B-cells when they encounter an antigen, the B-cells and T-cells jointly maintain a record of all encountered infections and thus strengthen and solidifies the bodies immune response to these infections.

Our innate immune response is quicker though non specific, it gets into action within hours and its pretty strong.

However when things get out of hand the innate system calls for help from the acquired immune system. This system can take days to mount a response, but the next time we encounter that pathogen it wont make us get sick.

In short everyday that we spend being healthy is all thanks to our immune system.

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