High School

Which of the following describes thymus-independent (TI) antigens?

A) They induce long-term immunological memory.
B) They induce a late antibody response that is predominantly IgG.
C) They contain repetitive epitopes on the surface of microorganisms.
D) They induce high-affinity antibodies through somatic hypermutation.
E) All of the above are correct.

21. A primary focus forms after a circulating naive B cell forms a conjugate pair with a T cell in the lymph node.

A) Medullary cords
B) TH1 cell in the B-cell zone
C) Cytotoxic T-cell in the T-cell zone
D) Follicular dendritic cell in the germinal center
E) TFH cell in the germinal center

22. Isotype switching in activated B-cells requires binding of MHC II on the B-cell with the T-cell receptor plus binding of:

A) B7 and CTLA4
B) CD40 and B7
C) CD40 and CD40L
D) CR2 and CTLA4
E) B7 and CD40L

23. In which of the following processes do Fc receptors play a role?

A) Opsonization
B) Deposition of complement
C) Antibody-dependent cell cytotoxicity
D) Priming of mast cells
E) All of the above are correct.

24. The process that drives an increase in antibody affinity for antigen is known as:

A) Apoptosis
B) Affinity maturation
C) Antibody-dependent cell-mediated cytotoxicity
D) Opsonization
E) Clonal expansion

25. The specific isotype/class antibodies switch to during B-cell activation relies on:

A) RAG1
B) TOT
C) Cytokines produced by TFH cells
D) B7 binding to CD28
E) Cytokines produced by stromal cells

Answer :

Final answer:

Thymus-independent (TI) antigens are a type of antigens that can activate B cells without the help of T cells. They can be divided into two categories: TI-1 antigens, which are microbial products that directly stimulate B cells, and TI-2 antigens, which are large, repetitive structures found on the surface of microorganisms. The antibody response to TI antigens is generally weaker and shorter-lived compared to thymus-dependent (TD) antigens.

Explanation:

Thymus-independent (TI) antigens are a type of antigens that can activate B cells without the help of T cells. They are characterized by their ability to induce an immune response without the need for T cell-mediated help. TI antigens can be divided into two categories: TI-1 antigens and TI-2 antigens.

TI-1 antigens are typically microbial products that directly stimulate B cells. They can activate B cells by binding to their B cell receptors (BCRs) and triggering intracellular signaling pathways. Examples of TI-1 antigens include lipopolysaccharides (LPS) and bacterial DNA.

TI-2 antigens, on the other hand, are large, repetitive structures found on the surface of microorganisms. They can crosslink multiple BCRs on a B cell, leading to B cell activation. Examples of TI-2 antigens include polysaccharides and glycolipids.

It is important to note that the antibody response to TI antigens is generally weaker and shorter-lived compared to thymus-dependent (TD) antigens, which require T cell help. This is because TI antigens do not induce long-term immunological memory and do not undergo somatic hypermutation, which is a process that generates high-affinity antibodies.

Learn more about thymus-independent (ti) antigens here:

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