2.5.10 Plasma & Memory Cells

Plasma Cells:

1. Role:

• Plasma cells are short-lived cells that secrete large amounts of antibodies specific to the antigen that triggered the immune response.

2. Characteristics:

• They are highly specialised for antibody production.
• Plasma cells do not divide but focus on producing antibodies to neutralise the pathogen.

3. Function:

• Antibodies produced by plasma cells:
• Bind to antigens to form antigen-antibody complexes.
• Neutralise toxins and block pathogens from infecting host cells.
• Trigger processes like agglutination and opsonisation to enhance pathogen destruction.

Memory Cells:

1. Role:

• Memory cells are long-lived cells that remain in the body after the infection has been cleared.
• They provide immunological memory, enabling a faster and stronger immune response upon re-infection with the same pathogen.

2. Characteristics:

• Memory cells are derived from both B cells and T cells.
• They do not produce antibodies immediately but divide rapidly upon exposure to the same antigen.

3. Function:

• Upon encountering the same antigen again:
• Memory B cells divide to produce plasma cells that secrete antibodies.
• Memory T cells rapidly activate to coordinate the immune response.
• This results in a secondary immune response that is:
• Faster (antibodies produced more quickly).
• Stronger (more antibodies produced).
• Longer-lasting than the primary response.

Comparison of Plasma Cells and Memory Cells:

Feature	Plasma Cells	Memory Cells
Lifespan	Short-lived (days to weeks).	Long-lived (years to decades).
Function	Produce and secrete large quantities of antibodies.	Remain in the body to provide long-term immunity.
Role in Immune Response	Active during the primary response to a pathogen.	Active during the secondary response to the same pathogen.

Importance of Plasma and Memory Cells:

1. Plasma Cells:

• Provide immediate protection by neutralising pathogens during the primary immune response.

2. Memory Cells:

• Enable long-term immunity and rapid responses during re-infection.
• Form the basis of vaccination, where exposure to a harmless form of an antigen generates memory cells without causing illness.