What is Antigen and Antibody with difference

Previously we have already discussed about what is immune system and immunity. So, today we will discuss about the antigen and antibody with their differences which is the part of our mechanism and we have seen it very short previously. So now we start with the definations of antigens and antibody.

Antigens: - The Antigens are the harmful substance that cause your immune system or immune response to produce Antibodies against it.

Bacteria, virus, chemicals are some examples of Antigens.

Antibodies: - Antibodies is a protective protein which is produced by the immune system in response to the harmful substance or a foreign substance called an Antigen. Antibody recognize Antigens and remove them from our body. 

we will also see working of antigen and antibody in blood.

Suppose there is a bacterium, there are many antigenic determinants on the surface of bacterium. on the other hand, antibodies are globular proteins or immunoglobulins that act specifically with antigen that stimulated its production. So, this is a bacterium antibody are specifically targeted against a specific antigenic determinant, there is a constant race between antigen antibody similar to that of prey predator relationship. Antibodies are involved in our different system that is actually protecting us from diseases whereas antigens are the disease-causing agents and there is a constant battle 24/7 battle and we'll be discussing detail, how these two molecules differ? and what makes the difference?

Structure of Antibody and Antigen binding region

Difference number 1: this is a clear-cut definition-Any substance or molecule that interact with antibodies or by t-cell receptor when complexed with MHC are called as antigens. Antigens include cell wall components of bacteria, capsules, flagella, toxin, viral proteins bacteria and other microbes etc. Theoretically any foreign body that incapable of eliciting an immune response can be called as an antigen. Whereas on the other hand antibodies are immunoglobulins synthesized by plasma cells of B cells that react specifically with antigen that stimulated its production. There are millions of antibodies inside our body that is specifically designed against different antigens in the surroundings.

Difference number 2: Chemically antigens are generally proteins, but can be carbohydrates, lipids or even nucleic acids in the case of viruses, may be carbohydrate polysaccharides can be antigenic, bacterial polysaccharides are antigenic these are some exceptions. Basically, they are proteins whereas antibodies on the other hand are glycoproteins made up of proteins and small amount of carbohydrates.

Difference number 3:  Antigenic structure is highly complex in structure and composition they differ greatly it may be simple to complex, you can see, these are different antigens, different shape, different molecular weight, different immunogenicity, many properties differ and each antigen will interact with a specific antibody This interaction is highly specific. Whereas in the case of antibody, individual units are Y shaped structure consisting of four polypeptide chains, two heavy chain and two light  chain that is joined by disulphide bond, and this is the structure, a y-shaped structure consisting of two heavy chain and two light chain and these chains are joined by disulphide bonds in between small amount of carbohydrates are also present and  these region constitutes an antigen binding site there are two antigen binding sites in an individual unit and this is called as a constant region or the FC region and this variable region determines the specificity of an antibody.

Difference number 4:  The region of the antigen that interacts with the antibodies is called as Epitopes. A pathogen has many epitopes. Suppose this is a bacterium and this bacterium has many epitopes or antigenic determinants that can interact specifically with different antibodies. This is the epitope number one, that is an antibody that is specifically directed against this epitope and this is epitope two, a different antibody that can fit this epitope will be synthesized by the system and this is epitope number three, where yet another different antibody will be produced specifically against this epitope. A single pathogen may be having a number of epitopes, On the other hand Antibody or variable region of the antibody that specifically binds with the epitope of an antigen is called as a paratope. Generally, a y-shaped antibody like IgG or individual monomeric unit has two identical paratopes and this is a structure of antigen is the Y shaped structure, this is the antigen binding site and this yellow coloured is a variable region and here the amino acids are highly specific and these amino acids can recognize the antigen that fits here and there is a high specificity. This region is called as the paratope. Paratope lies in the antigen binding region.

Difference number 5:  Antigens are actually causing diseases or allergic reactions whereas antibodies are involved in our Defence system They are the master molecules that is protecting us from diseases and they are continuously working 24/7 for protecting us from all infectious pathogens surrounding us. Protection is offered by immobilization or lysis agglutination, precipitation of antigenic material and this is one way, either by neutralization. suppose, this is a bacterium and antigens will bound to this bacterium and actually neutralizing it and toxin secreted by this bacterium and also Antibodies will bound all around these toxins and  actually neutralizing it and other way is opsonization, this will bound and actually causing the macrophages to phagocytose the pathogen entirely causing the destruction of the pathogen and that way is agglutination. this antibody will bind to the pathogen and causing clumping as a result, immune cells will clear this site. Clumping often results in other immune cells may get alerted and they will reach the site and clear the site and this results in elimination of pathogen from the site and these are different ways by which antibodies clear antigens from the system.

Structure of Antibody