In the world of Immunology the APC’s play a very precious role in body defense mechanisms. These are the group of immune cells which coordinate with other lymphocytes cells in order to protect the body from antigen or harmful substances which could be bacteria, viruses and any other unrecognized pathogens. 

APC’s are contributing cells that display antigen fenced by complex protein, a Major histocompatibility complex on its surface and the same process is known as antigen presentation and that is the key reason of calling this antigen presenting cells.  

APC’s are good helpers of T- cells and B- cells and other lymphocytes cells as it works as a  carrier of taking the antigen to the rapid response lymphocytes cells by presenting the same antigen on its surface and in follow- up antibodies generating cells take the charge for further defense mechanism.   

There are various kinds of APC’S present in the human body and these are Dendritic Cells, Macrophages Cells, B cells, Larghanes cells etc. 

Types of Antigen presenting cells( APCs) 

Antigen- presenting cells can be grouped into two categories: Professional and non- professional  APCs. 

Professional APC: These are the cells which co- ordinate with and recognise only MHC class II molecules because of its structure and function. Eg. Dendritic cells, B- cells, Larghanes cells, Macrophages Cells etc. 

Non- Professional APCs : These are the groups of cells which only intercept or express the MHC class I molecules. Eg. Cytotoxic T cells.

Professional APCs:

1. Dendritic cells-  It is a kind of APC which contains a wider range of antigen presentation and plays an important role in activation of T- cells and B- cells. It is commonly called as DCs. It has the ability to perform cross presentation as well which further helps the T- cells to be in activation mode. 

Dendritic cells exhibit considerably low levels of MHC class II among other professional APCs. It goes from the tissue of the lymph nodes whereby it meets and activates the T- Cells. 

1. Macrophages : It is also a APCs kind which can be stimulated by interferon which is a signaling protein manufactured and released by the host cells. It has the ability to express and demonstrate MHC class II  and co- stimulatory molecules. It usually circulates with the blood and enters into the affected areas and where it distinguishes as a macrophages from monocytes.  

The basic process is followed by the macrophages to surround the foriegn substances which may include bacteria, viruses etc. and create a distinct membrane within the cells over there the other breaking process carries out. 

1. B-Cells: B-cells are distinct in their features as they recognise specific kinds of proteins only, the receptors of B- cells are quite specific in its function. It can intercept or process the present peptides on the MHC class II molecules of its surface. 

B- cells undergo the formation of plasma and memory cells for the purpose of creating antigen for the body defense mechanisms. 

1. Langerhans Cells-   it is commonly abbreviated as (LC), these can be spotted at every layer of epidermis which is the outermost layer of the skin and are more noticeable in the stratum spinosum, a layer of skin found in between epidermis and stratum granulosum 

It is engaged in immune homeostasis as it displays or presents the antigen to the T- cells. The usages and its application can be seen when any skin infection occurs to any human body, it quickly spots the concerned antigen and displays it on its surface and sends it to the T- cells for further steps process. 

Functions and How APC interact with B- cells & T-cells

The function of APC’s are very comparable with the role of soldier at border, as soldier is always ready to spot the abnormal activities happening nearby posting and he reports the same to the headpost,  APCs work almost in the same fashion they spot the unrecognized foreign protein or substances and it to the competent lymphocytes like T- cells and B- Cells. 

APCs are similar like other defender cells but the role of these are slightly differentiable, when any anonymous and inconspicuous substance entering into human body would harm the body in serious manner and it equally difficult for the defense cells to identify the unknown substances. Hence, APCs like dendritic cells first spot the foreign particles or proteins and engulf the same within the cells and surround it by creating new membranes over there. 

Lysosome which is also known as suicidal bags of cell, responsible for the breaking of antigen spotted by the APCs. After the breaking of foreign proteins they present the same on its surface in order to activate the T- cells and B- cells and afterwards the T and B cells take the charge of killing the antigen by generating antibodies against them. 

 How does APC help in Cancer treatment? 

The key factor of causing cancer is uncontrollable divisions of malignant cells in the body and as APCs natural role is to send the message about the malignant and harmful foreign particles or proteins to T- cells. 

But while the body is suffering from this kind of serious disease, the body ‘s immune system automatically reaches a low level therefore, it becomes difficult for the APCs to react hence, doctors try to activate the APCs in order to intercept the cancer causing particles or substances

IMP321 is an APC used in cancer treatment to accelerate the immune system for better body response.  

 Conclusion 

Antigen presenting cells are very critical and important for the human body for effective functioning of the immune system as it acts as a carrier of foregin antigen to T- cells and other lymphocytes.  

APCs presents can be spotted at every epidermis layer of skin and that’s why it is in position to act promptly and inform about the same to other defenders of the body, certainly T- cells and B- cells of the body. 

APCs play an equal role in cancer treatment because of its function, doctors attempt to activate the APSc of cancer suffering patients to heal the body by the natural way.