Chapter 5 AI generated Flashcards
Describe cross-presentation in the immune system.
Cross-presentation is when different classes of antigen-presenting cells switch functions, allowing them to still catch clever pathogens even if the pathogens have found a way to avoid typical antigen-presenting cells.
Define CD1 protein in the context of MHC molecules.
CD1 proteins are non-classical MHC molecules that resemble MHC I but have grooves to bind lipids, which can also be recognized by T cells.
How do killer T cells contribute to organ transplant rejection?
Killer T cells are sensitive to foreign MHC molecules on transplanted organs, leading them to attack and kill the cells expressing these foreign MHC molecules.
Describe the role of TCRs in T cell activation.
TCRs (T cell receptors) are molecules on T cells that are crucial for recognizing specific antigens. They come in two flavors, AB and YD, and are responsible for initiating the activation of T cells.
Explain the difference between AB-TCRs and YD-TCRs in T cells.
AB-TCRs are considered traditional T cell receptors and are diverse, recognizing MHC molecules with proteins. YD-TCRs are non-traditional, less diverse, and often found in tissues like the intestine, uterus, and tongue.
What is the function of CD3 in T cell signaling?
CD3 is a complex of proteins added to TCRs to help signal to the nucleus for T cell activation. It consists of 4 proteins (Y, D, E, Z) with long cytoplasmic tails that aid in transmitting signals.
Describe the role of co-receptors CD4 and CD8 in T cell signaling.
CD4 and CD8 co-receptors function as clips that strengthen the adhesion between T cells and antigen-presenting cells. They also serve as intracellular signal molecules, enhancing the signal sent by the TCRs.
Explain the significance of clustering in T cell signaling.
Clustering in T cell signaling involves recruiting kinase enzymes to the tails of CD3 proteins, which then send signals to the nucleus. Different amino acid sequences in the CD3 complex can result in varied signals, influencing T cell responses.
Describe the process of T cell maturation in the thymus.
T cells start as double positive cells in the thymus, with one type of MHC molecule down-regulated as maturation progresses.
What is the role of B7 proteins in T cell activation?
B7 proteins on APCs bind to CD28 on T cells, providing co-stimulation for T cell activation.
Define immunological synapse.
It is the clustering and formation of TCRs and adhesion molecules between a T cell and an antigen-presenting cell during activation.
How does a Th cell help dendritic cells live longer during activation?
By plugging CD40L into CD40 on the DC, which prolongs the life of the dendritic cell.
Describe the role of IL-2 in T cell proliferation.
IL-2 is a cytokine produced by T cells that drives proliferation. Activated T cells respond to IL-2, leading to clonal selection.
What is the contribution of Th cells in the activation of killer T cells?
Th cells supply IL-2 for CTL proliferation, enhance CTL efficiency, and help generate memory killer T cells.
Explain the concept of effector cells in the context of CTLs and Th cells.
Effector cells refer to activated CTLs and Th cells that carry out immune responses. Th cells produce various cytokines, influencing immune reactions.
