Question

What do a plasma cell and a memory cell descended from the same \(\mathrm{B}\) cell have in common? How do they differ?

Short answer

Plasma cells and memory cells descended from the same B cell share the same genetic material and antigen specificity. Despite these common features, plasma cells differ by providing a primary immune response, characterized by producing and secreting large amounts of antibodies to combat pathogens, and typically they are short-lived. Memory cells, on the other hand, do not produce antibodies directly. Instead, these long-lived cells remember the pathogen that caused the infection and facilitate a faster and more potent response on subsequent exposures to the same pathogen.

Step-by-step solution

Identifying common features

Both plasma cells and memory cells are developed from the B cell lineage. Therefore, they share the same genetic material and antigen specificity. This means that they are designed to bind with the same specific antigen

Understanding what distinguishes plasma cells

Upon activation, B cells differentiate into plasma cells. These are the body's antibody factories, which are short-lived but secretes large amounts of antibodies in the primary immune response to eliminate the antigen.

Understanding what distinguishes memory cells

In contrast, memory cells do not produce antibodies directly. They are long-lived cells that remain in the body after an infection. When the same antigen enters the body again, they can rapidly differentiate into plasma cells to produce a stronger and quicker secondary immune response.

Key concepts

B cells

B cells, or B lymphocytes, are an essential part of the immune system. They play a crucial role in identifying and responding to pathogens like viruses and bacteria. B cells are produced in the bone marrow and are a key component of adaptive immunity, which provides specific responses to distinct antigens.
B cells have unique receptors on their surface, known as B cell receptors (BCRs). These receptors enable them to recognize specific antigens. When a B cell encounters an antigen that matches its receptor, it becomes activated. This activation is a vital step in the immune response process, as it signals the B cell to undergo differentiation into more specialized cells, such as plasma cells and memory cells. This ability to recognize a vast array of antigens allows B cells to mount effective immune responses to a wide variety of pathogens. Through this process, B cells are integral to maintaining the body's defenses against disease and infection. Their adaptability and specificity make them a cornerstone of immunological protection.

plasma cells

Plasma cells are specialized immune cells that develop from activated B cells. When a B cell is exposed to an antigen and becomes activated, it can differentiate into a plasma cell. Plasma cells are often referred to as the body's antibody-producing factories.
They are responsible for producing large quantities of antibodies, which are proteins designed to bind specifically to the antigen that stimulated the immune response. This antibody production is crucial during the primary immune response, helping to neutralize and eliminate pathogens from the body. Plasma cells are typically short-lived, and their primary function is to flood the bloodstream with antibodies.

• Short-lived: Plasma cells do not last long in the body.
• Antibody production: Their main role is to produce antibodies.
• Primary response: They help tackle the antigen quickly after first exposure.

This quick antibody production is essential for clearing infections and ensuring that the pathogens are removed from the system efficiently.

memory cells

Memory cells are another result of B cell activation but differ significantly from plasma cells in their function and longevity. After an infection is cleared, most plasma cells die off; however, some B cells persist as memory cells. These cells are long-lived and act as sentinels within the immune system.
Memory cells retain the information about the antigen that first stimulated the immune response. This memory allows for a quicker and more effective response if the same pathogen enters the body again. Upon re-exposure to the familiar antigen, memory cells can rapidly get activated and differentiate into plasma cells, bolstering an accelerated immune response, known as the secondary immune response.

• Long-lived: Memory cells can survive for years in the body.
• Rapid response: They enable fast and effective responses upon re-infection.
• Secondary response: Memory cells are crucial for a quicker immune response the second time around.

By preserving the memory of past infections, memory cells ensure that the immune system is prepared to protect the body effectively against repeated attacks from the same pathogens.