Basic Concept of Immunology

God’s creation!!! Damn. May be I only know the basics but still it's kinda amazing. For him, may be it's simply. Like if we look at a countries defence system, it's kinda simple for us. Border guards, army, air force, navy. All are kinda specific. Plus there are many grades. Like police at first, then army, then special branch bla bla. I think people has learnt all these from our body.

I want to cut to the chase. 'Immune system'. I think all of us at least familiar with this term after the Corona invasion. So Immunology is actually the branch that discuss about the mechanism of immune system. It's actually derived from te word 'Immunitas' that refers to protection for the senator from legal prosecution during their tenure. In small sense, it means protection. And obviously, our enemy is microbes and not only microbes, different foreign antigen(the substance that activate immune system). It can be protein molecule, macromolecules, polysaccarides as well. Basic examples are food. These food contain some of these elements that stimulate immune response.

In broader sense, our immune system is of two types. Innate( also known as natural, non-specific) and Adaptive( also known as acquired, specific).

Innate immune system is generally constitute of some components like

• Physiological barrier(Skin, GI tract, Respiratory tract)

• Biochemical barrier(Toxins, chemicals secreted by these parts)

• Leukocytes( eosinophil, basophil, macrophage, mast cell, dendritic cells, NK cells)

• Blood proteins

• Cytokines

Innate is actually the 1st defence system. More like guards who are always active. They won't let any intruder pass by. We all have this built in immune system. Generally, macrophage induces phagocytosis, mast cell releases histamin, dendritic cell cell capture microbes and present it to adaptive immune system. And NK cell is assassin. Direct boom boom killing. No mercy🔨.

(Not extending hard terms as none would understand)

And adaptive is like those police and army who are sitting under fan, waiting for someone to call and tell them to take actions. Main component is Lymphocyte. When microbes come in contact. They activates. Lymphocytes are of two types

• B lymphocyte

• T lymphocyte

And these two type maintain two different type of adaptive immunity

• Humoral

• Cell mediated

B lymphocytes actually produces antibodies. These antibodies recognise the microbes, neutrilize their toxins, target them and kill them. And T lymphocytes are of 3 types

• Helper T lymphocyte

• Cytotoxic T lymphocyte

• Regulatory T lymphocyte

Helper T lymphocyte activate innate immune system's macrophage. Then macrophage do his phagocytosis. Cytotoxic T cells are killers. Boom boom killing. And regulatory are like the referee. The tell them to stop. The microbe is already dead. One thing about T cell is it actually doesn't recognise the antigen. It recognises the peptide but not the naked peptide again. Peptide associated with Major Histocompatibility protein. That's why it is actually cell mediated cause it can't work on antigen itself. It works on antigen that is proliferating inside macrophages and antibody can't access. That's why it directly kill the infected cells. Boom boom.

And 😐 I forgot about the cytokines😅. Gotta recheck the topic. They are secreted by both innate and adaptive. Cytokines actually go to the site and facilitate inflammation and killing viruses. The accumulate different cells at the site of infection. That all I remember. I studied it at late night( around 2-3 am). So, my brain was exhausted probably. Gonna review that part.

I want to discuss about another interesting thing that is passive immunity. Do you know immunity can be passed by serum/plasma transfusion. Like these lymphocytes are actually part of blood and the antibodies they produces actually remains in the plasma portion. So, I have encountered some creepy microbe and my immune system beat the crap out of it by producing antibodies. If I give someone some of my serum that is containing antibodies, he can get the antibodies without getting the disease. One important example is the immunity of babies that is still in the womb. It takes some time for their immune system to grow but mom's antibodies goes in their body by placenta and protect them.

Actually, I have made a decision to write on something I read more frequently from now on actually. Because it will help me to review and let me know which information are out of my brain actually. I will be able to emphasize them properly.