[Biology Class Notes] on Difference between Humoral and Cell-Mediated Immunity Pdf [2024]

Humoral immunity and cell-mediated immunity is a part of active immunity. They are the mechanisms which protect our body against diseases when our innate immune system fails. As a part of active immunity, they take place after a couple of days the infection starts.

The Functions Include:

Recognition of specific non-self-antigens and presence of self-antigens.
Generate responses to eliminate specific pathogens or pathogen-infected cells.
Development of immunological cells.

In this topic, we will further discuss humoral immunity and cell-mediated immunity

and their differences.

What is Humoral Immunity?

Humoral immune activity is one of the mechanisms of the active immune system and is associated with circulating antibodies in contrast to cellular immunity. The wide range antibody activities is a response to rapid production of antigen-specific B cells during infections which increases antibody titres with enhanced affinity for the inciting agent and more directed and effective response.

What is Cell-Mediated Immunity?

Cell-mediated immunity is a type of adaptive immune response that does not involve antibodies but it does involve the activation of NK cell and macrophages and the production of antigen-specific cytotoxic T-lymphocytes and the release of several cytokines in response to a foreign antigen. Cell-mediated immunity plays an important role in controlling viral, chlamydia, rickettsia and protozoan infections such as trypanosomes as antibodies cannot penetrate and attack intracellular pathogens which multiply within the host cells.

Humoral and Cell-Mediated Immune Response

The humoral immune system starts with the production of proactive antibodies against infection or reinfection by common microorganisms such as staphylococci and streptococci. B- Lymphocytes, which have specific antigen receptors react when they come to contact with the specific antigen by producing plasma cells. These plasma cells produce antigen-specific antibodies and memory cells which enable the body to rapidly produce antibodies if the same antigen appears later. The differentiation of B-cells is stimulated by interleukin-2 (IL-2) which is secreted by CD4+ T cells and foreign antigens processed by macrophages.

Antibodies which are produced by plasma B-cells are found mainly in the blood spleen and lymph nodes and they eliminate antigens in several ways. Some of them are, by activating the complement system and neutralizing viruses and bacterial toxins. Another method is by coating the antigen by opsonization or forming an antigen-antibody complex to stimulate phagocytosis which promotes antigen clumping and prevents antigens from attaching to host cells.

The mechanism of cell-mediated immunity takes a different approach than humoral immunity. This mechanism protects the body through the following activities:

The response starts by activating antigen-specific cytotoxic T-lymphocytes or CTLs which can destroy body cells which show epitopes of foreign antigen on their surfaces such as cells with intracellular bacteria, cancer cells which show tumor antigens and virus-infected cells.
It also activates NK cells and macrophages which enable them to destroy intracellular pathogens.
The response stimulates the cells to produce a wide range of cytokines that regulates the function of other cells involved in adaptive immune responses and innate immune responses.

Cell-mediated immunity is directed primarily towards microbes which survive phagocytes and microbes that infect non-phagocytic cells. It also plays a major role in delayed transplant rejection.

Difference between Humoral Immunity and Cell-Mediated Immunity

There are various differences between humoral immunity and cell-mediated immunity

and we will discuss them below.

Cell-Mediated Immunity vs Humoral Immunity

Characteristics	Humoral Immunity	Cell-Mediated Immunity
Definition	Humoral immunity is mediated by macromolecules which are found in extracellular body fluids.	This type of immunity is mediated by the T-lymphocytes, NK cells and other immune system cells of the body.
Mediator	B-cells are involved in humoral immunity.	T-cells are the primary mediators of Cell-mediated immunity.
Components	The components include macrophages, B-cells and T-cells.	The components include T cells, cytotoxic T-cells, NK cells and macrophages.
Pathogen	Humoral immunity protects the body against extracellular pathogens and their toxins.	Cell-mediated immunity protects the body against intracellular pathogens.
Pathogen recognition	Recognises pathogens circulating in blood or lymph.	It responds to any cell that displays aberrant MHC markers which include cells invaded by pathogens, transplanted cells or tumor cells.
Antigen detectors	Antibodies and phagocytes are used to detect antigens.	MHC molecules on the cell surface and receptors are used to detect antigens.
Antigen binding	Antigens are not processed.	Antigens are processed and presented for T-Lymphocyte response.
Receptor involved	B-cell receptors are involved.	T-cell receptors are involved.
Accessory surface receptors/ molecules	Fc receptors, Igα, Igβ, , CD21, CD40	Integrins, CD3 molecular complex Dimer of ∑ chain, CD4, CD8, CD2, CD28,
T-cell involved	CD4+ T helper cells are involved.	CD4+ and CD8+ T cells are involved.
Antibodies formation	Antibodies are produced in the humoral response.	Antibodies are not formed.
Onset	The onset is rapid.	The onset is delayed.
Result	Plasma B cells are differentiated and secrete antibodies.	Cytokines are secreted.
Immunological surveillance	Immunological surveillance is absent.	Immunological surveillance is present.
Hypersensitivity reactions	Humoral immunity mediates hypersensitivity type I, II and III	Cell-mediated immunity regulates type IV hypersensitivity.
Role in grafting and organ transplantation	It may be involved in early graft rejection due to preformed antibodies.	Cell-mediated immunity participates in rejection of organ transplant.
Cancer immunity	Does not offer immunity against cancer.	Destroys cancerous and tumor cells and offers protection against cancer.
Assessment method	From plasma level of antibodies	Skin test for the development of a delayed type of hypersensitivity

Similarities Humoral and Cell-Mediated Immunity

The similarities between humoral and cell-mediated immunity are:

Both types of immunity systems are active immunities and have a lag period
Both humoral and cell-mediated are active against several types of pathogens.
Both immunity systems are not effective in immune-deficient individuals.

Humoral and Cell-Mediated Immunity: What’s the Difference?

Active immunity is the immunity instilled in organisms as a result of antigen exposure. It’s controlled by two distinct mechanisms:

Both immune routes attack pathogens in distinct ways, with different targets, components, and methods of killing them.

Continue reading to learn more about humoral and cell-mediated immunity, as well as the differences between the two.

Humoral Immunity vs Cell-mediated Immunity

In the table below, the distinction between humoral and cell-mediated immunity is shown.

Cell-mediated Immunity	Humoral Immunity
T-cells play a role in this.	B-cells play a role in this.
Antibodies do not develop.	Antibodies are produced.
Antigens are identified using receptors.	Antibodies are used to recognise antigens.
T-cell receptors bind to T-cells, which then adhere to antigens.	Antibodies made by B-cells cling to the antigen.
It defends against viruses, fungi, and other bacterial pathogens that live inside cells.	It guards against bacteria and viruses that live outside the cell.
Cell-mediated immunity involves both CD4+ and CD8+ lymphocytes.	In humoral immunity, only TH cells are involved.
Type IV hypersensitivity is mediated by this protein.	Hypersensitivity I, II, and III are all mediated by this protein.
It demonstrates a delayed response.	It has a quick response time.
It has the ability to destroy tumor cells, making it anti-cancer.	It is unable to eradicate tumor cells.

Immunity against Humoral Infection

Antibodies play a role in humoral immunity. It demonstrates a rapid response to infections. It’s the first line of defense against extracellular microbes trying to get into the host’s system. B-cells create antibodies that bind to antigens and neutralize bacteria.

The Immunity that is mediated by cells

T-helper and cytotoxic T-cells have a role in cell-mediated immunity. T-helper cells release cytokines that activate phagocytic cells, which phagocytose and destroy infections.

Similarities between Humoral Immunity and Cell-mediated Immunity

The parallels between cell-mediated and humoral immunity are as follows:

Immunity mediated by humor and immunity mediated by cells are both active immunities.
Both have a time lag.
Both have antibacterial capabilities and can be used to treat a variety of infections.
In both of them, immunological memories are present.
In immune-compromised patients, both systems are ineffectual.

There are a few distinctions between humoral and cell-mediated immune responses. Continue to visit ‘s website to learn more about the differences between humoral and cell-mediated immunity.