Block 9 Micro Mhc Antigen Presentation

MHC-II molecules are responsible for presenting antigens to CD4 T lymphocytes. CD4 T lymphocytes have a specific receptor, known as the T cell receptor (TCR), which recognizes antigens presented by MHC-II molecules. Therefore, CD4 T lymphocytes are the target of MHC-II-restricted antigen presentation.

CD8 T lymphocytes are the target of MHC-I-restricted antigen presentation. MHC-I molecules present antigens derived from intracellular pathogens or abnormal self-cells to CD8 T cells. This interaction activates the CD8 T cells, leading to their differentiation into cytotoxic T lymphocytes (CTLs) that can recognize and eliminate the infected or abnormal cells. CD8 T lymphocytes play a crucial role in cell-mediated immunity and are essential for the clearance of intracellular pathogens and the control of cancerous cells.

The maximum number of different MHC-I alleles that can be present on the cell surface of a normal, healthy individual is 6. This is because each individual has two copies of the MHC-I gene, one from each parent, and each copy can have up to three different alleles. Therefore, the total number of different alleles that can be present is 2 x 3 = 6.

Patients with bare lymphocyte syndrome are most likely to be vulnerable to all types of pathogens, including viruses, intracellular bacteria, extracellular protozoans, and extracellular bacteria. This syndrome is characterized by a deficiency in major histocompatibility complex (MHC) class I or class II molecules, which play a crucial role in presenting antigens to immune cells. Without functional MHC molecules, the immune system is unable to recognize and mount an effective immune response against a wide range of pathogens. Therefore, patients with bare lymphocyte syndrome are susceptible to infections caused by various types of pathogens.

The correct answer is Proteasome. Proteasomes are responsible for degrading proteins into peptides, which are then presented on MHC-I molecules for antigen presentation. This process is crucial for the immune system to recognize and respond to foreign antigens. Phagolysosomes, Golgi, peptidase, and nuclease are not directly involved in MHC-I-restricted antigen presentation.

Phagolysosomes are the source of peptides involved in MHC-II-restricted antigen presentation. Phagolysosomes are cellular compartments formed when a phagosome fuses with a lysosome. Within phagolysosomes, foreign particles, such as pathogens, are degraded by enzymes and proteases. This degradation process generates peptides that can then be presented on MHC-II molecules to activate immune responses against the specific antigens. Therefore, phagolysosomes play a crucial role in the presentation of antigens to immune cells.

The activation of CD8 T lymphocytes requires MHC class I antigen presentation, CD86 co-stimulation, and IL-12. MHC class I antigen presentation is necessary for the recognition of antigen by CD8 T cells. CD86 co-stimulation provides a second signal that is required for full activation of CD8 T cells. IL-12 is a cytokine that plays a crucial role in the differentiation and proliferation of CD8 T cells. Together, these elements are necessary for the activation of CD8 T lymphocytes.

The minimum number of different MHC-I alleles that can be present on the cell surface of a normal, healthy individual is 3. This is because MHC-I molecules are highly polymorphic, meaning they have multiple variants or alleles. Each individual inherits two MHC-I alleles from their parents, one from each parent. Therefore, the minimum number of different MHC-I alleles would be 3, as an individual could inherit two different alleles from one parent and one allele from the other parent.

B lymphocytes, macrophages, and dendritic cells are all antigen presenting cells involved in MHC-II-restricted antigen presentation. These cells play a crucial role in the immune response by capturing, processing, and presenting antigens to CD4 T lymphocytes. B lymphocytes are responsible for producing antibodies, while macrophages and dendritic cells are specialized in phagocytosis and antigen presentation. CD4 T lymphocytes recognize antigens presented on MHC-II molecules and initiate immune responses against pathogens. Therefore, all three cell types are essential for effective immune responses against foreign invaders. CD8 T lymphocytes, on the other hand, are primarily involved in MHC-I-restricted antigen presentation.

B lymphocytes, macrophages, and dendritic cells are all antigen presenting cells involved in MHC-I-restricted antigen presentation. These cells play a crucial role in the immune response by capturing, processing, and presenting antigens to CD8 T lymphocytes. B lymphocytes can present antigens to CD8 T lymphocytes through MHC-I molecules, while macrophages and dendritic cells are also capable of presenting antigens through MHC-I molecules. These antigen presenting cells are essential for activating the cytotoxic response of CD8 T lymphocytes, leading to the elimination of infected or abnormal cells.

Depending if you have a TH1, TH2 or a TH17 response., D and F could also be correct answers

Surprisingly, people with MHC-I deficiency are not abnormally affected by viral and other intracellular infections. This is because MHC-I deficiency is mainly due to mutations in TAP-1/TAP-2, and that there probably exist compensatory pathways for peptide transport.