Difference between humoral immunity and cell mediated immunity

The primary difference between them is the mechanism of immunity, where the Humoral immunity produces antibodies against the antigens which are present outside the infected cells or free circulating in the blood. Cell-mediated immunity works inside the infected cells, where it destroyed the pathogens or microorganisms by the process of lysis by the releasing cytokines.

Humoral immunity shows quick response against the pathogens, while cell-mediated immunity is slow in action. Both the type are part of the adaptive immune system. Our immune system provides the protection and resistance against the infectious disease, which is offered by the host cell present in the body.

The immune system has complex networks of the molecules, cells and their interactions are designed to eradicate the infectious organisms from the body. Immunity or immune system is divided into two types – innate (non-specific) and acquired or adaptive (specific) immunity.

The innate immunity works as defensive barriers and represents the capability of the organisms to protect against any disease. On the other hand, the acquired immunity represents the most potent line of defense mechanisms in the body, which is known for identifying and destroying the specific pathogens or any foreign particles which are harmful to the body.

The acquired or adaptive immunity display four major characteristics, like Recognition diversity; Immunological memory; Antigen specificity; and Discrimination among self and non-self.

In this content, we will be studying the Humoral and the cell-mediated immunity, which is the part of the adaptive or acquired immunity. We will also focus on the points on which these terms distinguish, with a brief summary.

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Definition of Humoral Immunity

Humoral immune response or antibody-mediated response is associated with the B cells, where the role of these cells (B cells) is to identify the antigens or any foreign particle that are present in the circulation in blood or lymph. This immune response is also assisted with helper T cells which along with the B cells get differentiated into plasma B cells that can produce antibodies.

As soon as B cells produce antibodies, they will bind to an antigen; neutralize them and causes phagocytosis or cell lysis (destruction of the cells). The antigen is the foreign particle, which is usually a carbohydrate or a protein that triggers an immune response, but above that our body has tremendous capability to identify the antigens.

Any kind exposure of antigens leads to the development of secondary immunological response which increases the level of the immune response. The immunoglobulins or antibodies mediate the humoral immunity, these are a particular group of proteins produced by the B-lymphocytes.

This following points can explain the eventual process:

• Antigens triggers to the body.
• Antigens bind to the B cells present in the blood circulation.
• Helper T cells or Interleukins assist the B cells and initiate B cell proliferation which activates plasma B cells.
• Plasma cells carry antibodies which are antigen-specific and has specific binding receptors of the activated B cells.
• These antibodies travel throughout the body and bind to the antigens.
• The B cells after destroying the antigens, produce memory cells which in turn provide future immunity when the same antigen triggers the body again.

Definition of Cell-Mediated Immunity

T lymphocytes assist the Cell-mediated immunity or cellular immunity. In this type, cytokines have released that help to activate the T cells which further destroys the infected cell. Likewise the B cells, T cells originate in bone marrow but matures in the thymus and later gets circulate in the bloodstream and lymphoid tissue.

The antigen present on the surface of the antigen-presenting cells (APCs) with the abnormal Major Histocompatibility Complex (MHC) proteins. Abnormal or aberrant MHC molecules are formed from the antigens which have been destroyed or broken down or from any infected virus (exogenous antigens) or the from tumour cells that are actively producing foreign proteins (endogenous antigens).

Now helper T-cells release the cytokines, that will activate the T cells, which will recognize the aberrant MHC-antigen complex and will bind to it and differentiate into cytotoxic T cell. After this cell will undergo lysis (cell destruction).

This following points can explain the eventual process:

• Antigen-presenting cells (APCs) will display the antigens present on its surface and binds to T cells.
• Interleukins (secreted by helper T cells) facilitates the activation of T cells.
• Along with the MHC-I and the endogenous antigens, the T cells proliferate and produce the cytotoxic T cells.
• The T cells destroy the infected cells exhibiting antigens.
• In case of exogenous antigens and MHC-II displayed on the plasma membrane together, the T cells trigger to proliferate helper T cells which release interleukins and cytokines and also arouse the B cells to produce antibodies against them. This process is also supported by the natural killer cells (NK) and macrophages, which destroys the antigens.

Key Differences Between Humoral and Cell-Mediated Immunity

Following are the main points which display the difference between the humoral and the cell-mediated immunity:

1. The humoral immunity is associated with the B-lymphocytes and is responsible for destroying the pathogens by producing antibodies against it, whereas the cell-mediated immunity is associated with the T-lymphocytes and is responsible for the destroying the pathogens or microorganism which have invaded the cells without producing antibodies.
2. Humoral immunity is intimately associated with B-lymphocytes, T-lymphocytes, and macrophages, on the contrary, the cell-mediated immunity is associated with T-lymphocytes, helper T cells, natural killer cells, and macrophages.
3. Humoral immunity plays a major role in recognizing antigen or any foreign particle and in producing antibodies against it. It is known for working against extracellular pathogens.
4. Cell-mediated immunity is related to T-lymphocytes, which work by identifying viruses and microorganisms, thus destroying them by the cell lysis or phagocytosis or pinocytosis. It is known for working against intracellular pathogens.
5. Humoral immunity secretes antibodies to fight against antigens, whereas cell-mediated immunity secretes cytokines and no antibodies to attack the pathogens.
6. The Humoral immunity is rapid or quick in their action against antigens, while the Cell-mediated immunity show delay though permanent action against any pathogens.
7. Humoral immunity mediates hypersensitivity type I, II, and III, whereas cell-mediated is delayed in response and mediates hypersensitivity type IV.
8. Humoral immunity is involved in an early stage of graft rejections due to the formation of antibodies against any foreign particle, while Cell-mediated immunity is involved in the rejection of organ transplants after a certain time as they show delayed response.

Conclusion

From the above content, we came to know about the few though critical differences between the two types of the active immune system which are a humoral and cell-mediated immune response. We concluded that both the types of immunity differ in the process of destroying the pathogens, where antigens specific antibodies are produced rapidly against the antigens, while in cell-mediated immunity the pathogens are destroyed through cell lysis.