Vaccines and the Immune Response: How Vaccines Work

Summary

Influenza vaccines trigger an immune response by mimicking viral infection through inactivated virus particles or viral components like hemagglutinin (HA) and neuraminidase (NA). Upon injection, these components stimulate immune cells, including macrophages, T lymphocytes, and B lymphocytes. Macrophages break down the viral particles, displaying antigens on their surface, which activates T cells. Helper T cells assist B cells in producing antibodies, while memory B cells ensure a rapid response upon future exposure to the virus. This process helps prevent or reduce the severity of influenza when exposed to live virus.

Takeaways

• 😀 Vaccines mimic viral infections to trigger an immune response, helping the body prepare for future exposure to the virus.
• 😀 Influenza vaccines are made using inactivated or killed virus particles, often taken from various circulating influenza strains.
• 😀 The vaccine contains hemagglutinin (HA) and neuraminidase (NA) components, which are foreign antigens recognized by the immune system.
• 😀 In Canada, influenza vaccines are typically administered via intramuscular injection.
• 😀 Once injected, the vaccine's foreign antigens enter the bloodstream, triggering an immune response involving various immune cells like macrophages, T cells, and B cells.
• 😀 Macrophages play a critical role by ingesting hemagglutinin and presenting it on their surface along with the MHC receptor, triggering T cell activation.
• 😀 Activated T cells proliferate into cytotoxic, helper, or suppressor T cells, helping the immune system fight off potential infections.
• 😀 Helper T cells assist in generating antibodies and activating memory B cells, which help the immune system remember the virus for future encounters.
• 😀 B cells, unlike T cells, can ingest hemagglutinin directly and, upon activation by helper T cells, produce antibodies specific to the viral strain in the vaccine.
• 😀 Memory B cells are important for quicker and more efficient immune responses if the body is exposed to the virus again in the future.
• 😀 When a person is exposed to the influenza virus through droplets from an infected person, hemagglutinin antibodies from the vaccine can block viral attachment and reduce disease severity or prevent illness.

Q & A

How do influenza vaccines trigger an immune response?

Influenza vaccines trigger an immune response by mimicking a viral infection. They contain inactivated or killed virus particles, or viral components, such as hemagglutinin (HA) and neuraminidase (NA), which stimulate the immune system.

What are the main components found in influenza vaccines?

Influenza vaccines typically contain inactivated or killed virus particles, including the sub-viral components hemagglutinin (HA) and neuraminidase (NA), which are key to triggering an immune response.

How are influenza vaccines administered in Canada?

In Canada, influenza vaccines are administered through intramuscular injection.

What is the role of macrophages in the immune response to the influenza vaccine?

Macrophages play a key role by ingesting hemagglutinin from the vaccine. After internalizing it, they break it into smaller components and display these on their surface, which helps activate T cells.

What happens after macrophages display hemagglutinin on their surface?

Once macrophages display hemagglutinin on their surface in combination with the major histocompatibility complex (MHC), T cells recognize and bind to the antigen-MHC complex, which activates T cells.

What are the different types of T cells activated by the influenza vaccine?

T cells activated by the vaccine proliferate into several types, including cytotoxic T cells, regulatory T cells, and helper T cells, each having a different role in the immune response.

How do helper T cells contribute to the immune response after vaccination?

Activated helper T cells express specific hemagglutinin receptors and are crucial for generating antibodies and activating memory B cells, which play an important role in long-term immunity.

How do B cells contribute to the immune response triggered by influenza vaccines?

B cells ingest hemagglutinin independently of the MHC, process it, and present it on their surface in combination with MHC. Helper T cells then interact with these B cells, triggering their proliferation and differentiation into plasma cells or memory B cells.

What is the function of plasma cells in the immune response to the influenza vaccine?

Plasma cells produced by activated B cells generate antibodies specific to the influenza virus strain in the vaccine, which helps neutralize the virus in future exposures.

How do memory B cells assist in future immune responses against influenza?

Memory B cells remember the specific influenza strain from the vaccine and enable a quicker, more effective immune response if the body is exposed to the virus in the future.

How do antibodies from the vaccine help prevent influenza infection?

Antibodies, particularly those against hemagglutinin, block the influenza virus from attaching to host cells in the nasopharynx, preventing viral colonization and reducing the severity or preventing the disease entirely if exposed to the virus.