noc19 bt23 lec48 Adaptive Immune Response and Vaccine

Summary

In this lecture, Prof. Rachit Agarwal explores the immune response to biomaterials, focusing on the adaptive immune response and its role in drug delivery and tissue engineering. He discusses the balance between clotting and clot degradation, the function of dendritic cells and macrophages, and the activation of T-cells and B-cells. The lecture also covers the impact of biomaterials on the immune system, the challenges of using natural and synthetic polymers in medical applications, and the use of adjuvants in vaccines to stimulate immune responses. The importance of prophylactic and therapeutic vaccines in healthcare is highlighted, emphasizing their role in disease prevention and treatment.

Takeaways

• 🩸 The lecture discusses the immune response to materials, focusing on the adaptive immune response and its specificity compared to the innate immune response.
• 🧫 Blood clotting is a physiological response to injury, primarily mediated by platelets, and the clot degradation is initiated by tissue activators to prevent bleeding.
• 🛡️ Tissue activators can be used to prevent surface fouling in medical implants but must be carefully balanced to avoid inhibiting necessary blood clotting.
• 🔬 Dendritic cells and macrophages play a crucial role in linking the innate and adaptive immunity by processing and presenting antigens to T-cells.
• 🔄 T-helper, cytotoxic T-cells, and T-regulatory cells are key leukocytes in the adaptive immune response, each with specific roles in activation and regulation.
• 🧬 B-cells are responsible for antibody production, which can tag or neutralize toxins and pathogens within the system.
• 🔑 Antigen-presenting cells use class I and class II pathways to load and present antigens, which are critical for activating T-cells and B-cells.
• 🚫 The immune system requires at least two signals for activation, preventing unwanted responses to self-antigens and ensuring a targeted response to foreign antigens.
• 🧪 Biomaterials, especially natural polymers, can trigger an adaptive immune response, which can affect the functionality of implants or delivered drugs.
• 💉 Vaccines are designed to generate an immune response against specific antigens, using adjuvants to stimulate and amplify the immune response.
• 🏥 Vaccines are categorized as prophylactic, given before disease exposure, or therapeutic, used to bolster the immune response during an active disease.

Q & A

What is the primary function of platelets in the context of blood clotting as discussed in the lecture?

Platelets primarily function to prevent bleeding by forming a fibrin mesh at the site of injury, which is a normal physiological response to injury.

How do endothelial cells contribute to the healing process after blood clotting?

Endothelial cells contribute to the healing process by clearing away the clot once it has served its purpose and healing has started, through the action of tissue activators that initiate clot degradation.

What is the role of tissue activators in preventing surface fouling when applied to a material?

Tissue activators can prevent surface fouling by preventing fibrin from forming a polymer on the material's surface, thus avoiding the obstruction that could hinder the material's function.

How does the adaptive immune response differ from the innate immune response?

The adaptive immune response is specific and adapts to the particular infection, unlike the innate immune response, which provides a generic response to a wide range of pathogens.

What is the function of dendritic cells and macrophages in the immune system?

Dendritic cells and macrophages serve as a link between the innate and adaptive immunity by secreting molecules, presenting antigens, and activating the rest of the immune system.

What are the main types of leukocytes discussed in the lecture and what are their roles?

The main types of leukocytes are T-helper cells, cytotoxic T-cells, T-regulatory cells, and B-cells. T-helper cells aid in the activation of T-cells, cytotoxic T-cells are responsible for killing aberrant or foreign cells, T-regulatory cells prevent autoimmunity, and B-cells produce antibodies.

How does the class I antigen loading pathway function in the immune response?

Class I antigen loading involves the degradation of proteins within the cell's cytoplasm and their presentation on the cell membrane to be recognized by immune cells like CD8 positive T-cells, which are responsible for killing cells that present such antigens.

What is the significance of the two-signal requirement for the activation of leukocytes?

The two-signal requirement ensures that the immune response is only activated in the presence of a foreign antigen and not against self-antigens, preventing autoimmunity and ensuring a targeted response to pathogens.

How can synthetic polymers like PEG potentially cause an immune response?

Although synthetic polymers like PEG are expected not to be recognized by the immune system, they can still cause an immune response by being processed as antigens, leading to the production of antibodies against them.

What are adjuvants and how do they enhance the immune response in vaccines?

Adjuvants are molecules that stimulate the immune response by providing a co-stimulatory signal, which is necessary along with the antigen presentation to activate the immune system effectively.

What is the difference between prophylactic and therapeutic vaccines?

Prophylactic vaccines are given before disease exposure to create immunity, while therapeutic vaccines are administered after disease onset to strengthen the immune system to fight the active disease.