Question 1

Which of the following is characteristic of the primary immune response (first encounter with an antigen)as compared with the secondary immune response (later encounter with the same antigen)?

Accepted Answer

The primary immune response is characterized by a higher production of IgM antibodies compared to the secondary immune response, which predominantly involves IgG antibodies and is faster and more robust due to the presence of memory cells.

Question 2

Specialized antigen- presenting cells such as macrophages, dendritic cells, and B cells are the only cells to possess class II MHC antigens, while almost all of the remaining nucleated cells in the body possess class I MHC antigens.

Accepted Answer

Class II MHC antigens are indeed primarily expressed by specialized antigen-presenting cells such as macrophages, dendritic cells, and B cells, which play a key role in the immune response by presenting antigens to T cells. In contrast, Class I MHC antigens are found on almost all nucleated cells in the body, allowing these cells to present endogenous antigens to cytotoxic T cells.

Question 3

There are five basic steps of phagocytosis. List them and briefly describe them.

Accepted Answer

The answer of There are five basic steps of phagocytosis....

Question 4

T lymphocytes can react directly against foreign antigens they encounter. For example, if they encounter a bacterium, they will be stimulated to cytotoxic activity.

Accepted Answer

T lymphocytes recognize antigens in the form of peptides presented on the surface of cells by major histocompatibility complex (MHC) molecules, rather than reacting directly to intact foreign antigens like bacteria.

Question 5

The cytokine that activates macrophages, inhibits viral replication, and increases MHC Class I expression is interferon.

Accepted Answer

Interferons are a group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells. They play a crucial role in the immune response by activating macrophages, inhibiting viral replication, and increasing the expression of MHC class I molecules, thus enhancing the presentation of viral antigens to T cells.

Question 6

Which of the following can function as antigen presenting cells?

Accepted Answer

Dendritic cells, B cells, and macrophages can all function as antigen-presenting cells (APCs). They play a crucial role in the immune response by processing and presenting antigens to T cells.

Question 7

The positive acute phase reactant responsible for binding and inactivating certain drugs is alpha- 1 acid glycoprotein.

Accepted Answer

Alpha-1 acid glycoprotein (AAG) is a positive acute phase reactant that increases in concentration during acute phase response and is known for its drug-binding properties, particularly binding and inactivating certain drugs by affecting their distribution and bioavailability.

Question 8

Which statement below is TRUE regarding B lymphocytes?

Accepted Answer

B memory cells, a type of B lymphocyte, can indeed live for years and have the ability to quickly reactivate upon re-encountering the same antigen, providing a rapid and robust immune response. This is a key feature of the adaptive immune system, allowing for long-term immunity against previously encountered pathogens.

Question 9

Briefly describe positive and negative selection of T cells in the thymus.

Accepted Answer

The answer of Briefly describe positive and negative selection of...

Question 10

Why do phagocytes dramatically increase metabolic rate and oxygen consumption when they begin phagocytosis?

Accepted Answer

The answer of Why do phagocytes dramatically increase metabolic rate...

Question 11

Microbes and/or their products (endotoxins and lipopolysaccharides)are the underlying cause of all inflammations.

Accepted Answer

Not all inflammations are caused by microbes or their products; inflammation can also result from non-infectious factors like physical injury, autoimmune reactions, or exposure to irritants.

Question 12

If a naive T cell does not encounter its corresponding antigen within a few days, what happens?

Accepted Answer

Naive T cells that do not encounter their specific antigen within a certain timeframe typically undergo apoptosis, or programmed cell death, as they are not activated to become effector or memory T cells.

Question 13

Fibronectin, C- reactive protein, antibodies, and complement fragment C3b can all function as opsonins.

Accepted Answer

Opsonins are molecules that enhance phagocytosis by marking foreign particles for an immune response, and fibronectin, C-reactive protein, antibodies, and complement fragment C3b all serve this function by binding to foreign particles and promoting their recognition and ingestion by phagocytes.

Question 14

How does a T cytotoxic lymphocyte recognize that a host cell is infected with a virus?

Accepted Answer

The answer of How does a T cytotoxic lymphocyte recognize...

Question 15

The process by which certain substances function to attract leukocytes to an tissue where they're needed is called ________.

Accepted Answer

The answer of The process by which certain substances function...

Question 16

Which molecules on the cell surfaces of transplanted tissue are most important to match to the recipient to immediately prevent the recipient's T cells from recognizing the transplanted tissue as foreign?

Accepted Answer

The Major Histocompatibility Complex (MHC) Class I molecules are crucial for matching in transplants because they are present on almost all nucleated cells and are recognized by the recipient's cytotoxic T cells, which can lead to rejection if they are seen as foreign.

Question 17

When the immune system initiates an inflammatory response, this is always beneficial to resolving the injury or infection.

Accepted Answer

While inflammation is a crucial part of the body's defense mechanism against injury and infection, excessive or chronic inflammation can lead to tissue damage and contribute to various diseases, such as arthritis, heart disease, and diabetes.

Question 18

Outline the basic steps in the gene rearrangement necessary to produce the T cell antigen receptor and state how this contributes to the ability of T cells to respond to various antigens.

Accepted Answer

The answer of Outline the basic steps in the gene...

Question 19

In an inflammatory reaction, increased vascular permeability causes escape of the fluid into the tissues resulting in ________.

Accepted Answer

The answer of In an inflammatory reaction, increased vascular permeability...

Question 20

A mature T helper cell should possess CD2, CD3, and CD4.

Accepted Answer

Mature T helper cells express CD2, CD3, and CD4 molecules on their surface, which are crucial for their function in the immune response. CD2 and CD3 are involved in T cell activation, while CD4 serves as a co-receptor that enhances the interaction between the T cell and antigen-presenting cells.

Quiz 2: Overview of the Immune System

Which of the following is characteristic of the primary immune response (first encounter with an antigen) as compared with the secondary immune response (later encounter with the same antigen) ?