What is the Difference Between Effector and Memory Cells

The main difference between effector and memory cells is that effector cells are short-lived cells whereas memory cells are long-lived cells.

Effector cells and memory cells are two types of cells in the immune system. Generally, T and B lymphocytes serve as effector cells and memory cells in the immune system.  

Key Areas Covered

1. What are Effector Cells
– Definition, Types, Function
2. What are Memory Cells
– Definition, Types, Function
3. Similarities Between Effector and Memory Cells
– Outline of Common Features
4. Difference Between Effector and Memory Cells
– Comparison of Key Differences

Key Terms

Effector Cells, Memory Cells

What are Effector Cells

Effector cells are the T and B lymphocytes of the immune system that serves in normal immune function. Generally, there are two types of T lymphocytes: cytotoxic T cells and helper T cells. Cytotoxic T cells are responsible for killing virus-infected cells. These cells contain CD8+ receptors that recognize antigens presented with the MHC class I molecules. Upon recognition, cytotoxic T cells induce apoptosis and degranulation in infected cells. Helper T cells, on the other hand, contain CD4+ receptors that recognize antigens presented with the MHC class II molecules. Generally, helper T cells recognize antigens presented in antigen-presenting cells such as macrophages, dendritic cells, and neutrophils. The main function of helper T cells is to activate other cells in the immune system to mount an immune response.

Figure 1: Destruction of Infected Cells

Furthermore, the other type of effector cells is effector B cells. Normally, effector B cells are also called plasma B cells. The main function of plasma B cells is to secrete antibodies in humoral immune response and to activate cytotoxic and helper T cells to generate a cell-mediated immune response.

What are Memory Cells

Memory cells are the long-lived cells in the immune system that have the ability to recognize antigens previously recognized by the immune system. Their recognition of antigens for the second time allows mounting a faster and stronger immune response. Usually, the two types of memory cells are memory T cells and memory B cells. Memory B cells are clones of parent B cells that previously worked as antigen-presenting B cells. Further, these B cells are activated by T cells to proliferate. Since they are a clone of a parent B cell, memory B cells contain the same B cell receptors as the parent B cell. Therefore, they detect the same antigen that the parent B cell encountered.

Figure 2: Activation of T and B Cells

Moreover, memory T cells are T lymphocytes that also recognize previously encountered antigens. Unlike B lymphocytes, T cells do not produce antibodies. There are four types of memory T cells: central memory T cells, effector memory T cells, tissue-resident memory T cells, and virtual memory T cells. Normally, central memory T cells and effector memory T cells occur in lymph nodes and peripheral circulation. Tissue-resident memory T cells occur in tissues while virtual memory T cells occur in clonal expansion events.

Similarities Between Effector and Memory Cells

• Effector and memory cells are two types of cells in the immune system.
• They differ in their lifespan and function in the immune system.
• B and T lymphocytes serve as effector cells and memory cells.

Difference Between Effector and Memory Cells

Definition

Effector cells refer to relatively short-lived activated cells that defend the body in an immune response while memory cells refer to long-lived lymphocytes capable of responding to a particular antigen on its reintroduction, long after the exposure that prompted its production.

Life Span

Moreover, effector cells are short-lived cells while memory cells are long-lived cells.

Function

Effector cells defend the body in response to an immune response while memory cells recognize and mount an immune response to a previously encountered antigen.

Conclusion

In brief, effector cells and memory cells are two types of cells in the immune system. T and B lymphocytes usually serve as effector cells and memory cells. In general, effector cells are short-lived cells while memory cells are long-lived cells. The main function of the effector cells is to mount an immune response to a particular pathogen. In general, effector T cells either kill infected cells or help B lymphocytes to produce antibodies against antigens while effector B lymphocytes produce antibodies against pathogens. Memory cells, on the other hand, recognize and mount immune responses against a previously recognized antigen. Therefore, the main difference between effector and memory cells is their lifespan and function.      

References:

1. “Effector Cell.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 
2. “Memory Cell.” Biology Articles, Tutorials & Dictionary Online, 16 June 2022

Image Courtesy:

1. “CD8+ T cell destruction of infected cells” By Dananguyen – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Activation of T and B cells” By Immcarle105 – Own Work (CC BY-SA 4.0) via Commons Wikimedia