Antigens And T Cells Quiz

B7 interacts with CD28 and cd28. CD28 is a protein receptor found on the surface of T cells, and it plays a crucial role in T cell activation. B7, also known as B7-1 and B7-2, is a protein ligand found on the surface of antigen-presenting cells. When CD28 on T cells binds to B7 on antigen-presenting cells, it provides a co-stimulatory signal that enhances T cell activation and proliferation. This interaction is important for the initiation of an effective immune response against pathogens.

Dendritic cells, macrophages, and B cells are professional antigen presenting cells. Dendritic cells are specialized in capturing and presenting antigens to activate T cells. Macrophages are responsible for engulfing and digesting pathogens, and then presenting the antigens on their surface to activate immune responses. B cells, on the other hand, are involved in the production of antibodies and can also present antigens to T cells. Together, these three cell types play a crucial role in initiating and coordinating immune responses against pathogens.

The correct answer is B and C only because T cell receptors can only recognize peptide antigens bound to MHC molecules and they are also membrane-bound glycoproteins. They cannot recognize any antigen and do not have multiple antigen binding sites.

Cyclosporin is a medication that inhibits the production of IL-2, also known as IL2 or il2. IL-2 is a cytokine that plays a crucial role in the expansion and activation of T cells. By blocking the production of IL-2, Cyclosporin effectively prevents the proliferation of T cells, which is beneficial in conditions where an overactive immune response, such as in organ transplantation or autoimmune diseases, needs to be controlled.

Superantigens are toxins that can bind simultaneously to the T cell receptor (TCR) and major histocompatibility complex class II (MHC II) molecules, forming a bridge between them. This interaction leads to the activation of a large number of T cells, causing them to divide and differentiate. Therefore, superantigens are responsible for the excessive activation of the immune system, leading to harmful effects such as inflammation and tissue damage.

CD4TH2 cells, also known as helper T cells type 2, play a crucial role in the immune response by assisting B cells in their transformation into plasma cells. These plasma cells are responsible for producing and secreting antibodies, which are essential for fighting off infections. CD4TH2 cells release specific chemical signals called cytokines that activate B cells, promote their proliferation, and enhance antibody production. Therefore, CD4TH2 cells are essential in the adaptive immune response and contribute to the body's ability to defend against pathogens.

T cells are a type of white blood cell that plays a critical role in the immune response. They recognize and bind to antigens, which are molecules found on the surface of pathogens or infected cells. This binding triggers T cells to initiate a defense mechanism, either by directly attacking infected cells or by coordinating other components of the immune system to respond. T cells do not produce antigens or destroy them; they detect antigens and respond accordingly.

The correct answer is "can undergo somatic recombination." Somatic recombination is a process that occurs during T cell development, where gene segments encoding the variable regions of the T cell receptor (TCR) are rearranged to generate a diverse repertoire of TCRs. This allows T cells to recognize a wide range of antigens. Somatic recombination is a crucial mechanism for generating T cell diversity and is unique to T cells.

ssRNA viruses are recognized by Toll-like receptor 3 (TLR 3) and Toll-like receptor 7 (TLR 7). These receptors are part of the innate immune system and are responsible for detecting viral nucleic acids. TLR 3 specifically recognizes double-stranded RNA, while TLR 7 recognizes single-stranded RNA. Therefore, when a ssRNA virus infects a host, it activates both TLR 3 and TLR 7 to initiate an immune response against the virus. The other options mentioned in the question (TLR 2 and TLR 4, B7 and CD28) are not involved in the recognition of ssRNA viruses.