Intrigue at the Immune Synapse - Assignment Example

Scientific American Current Issues in Microbiology Article: “Intrigue at the Immune Synapse” Due 11:59 PM on Monday, April 16th Why is the communication at the immune synapse so important? What types of problems can occur if the communication at the immune synapse is not correct? Explain. The communication at the immune synapse is essential because it allows the immune cell to recognize another cell as either a normal, healthy cell or an abnormal, sick, infected cell. This then stimulates the immune cell to activate an immune response to kill the sick cell.

If incorrect communication occurs at the synapse, the immune cell may mistake a healthy cell to be sick, triggering an attack on normal tissues. This manifests as autoimmune disease. On the other hand, if incorrect communication makes the immune cell perceive a sick cell to be healthy, this allows abnormal tumor cells to survive and can lead to cancer. This also allows the persistence of infectious organisms inside cells, leading to chronic infections.2. A major infectious disease spreading among college students is AIDS.

How may HIV exploit immune synapses to spread?HIV may hijack the infected immune cell’s machinery to set up ‘viral synapses’, which mimic the immune synapse, and allow the viral particle to cross over at the synapse to a non-infected cell.3. What technological advances allowed scientists to visualize immune synapses and demonstrate their existence?The development of high-resolution microscopy techniques and computer enhancement of previously used imaging methods to create three-dimensional images has allowed visualization and observation of immune synapses.4. What is the possible function of nanotubes that form between cells of the immune system?

The possible function may be communication between immune cells that are far apart, by allowing the transfer of signaling molecules such as cytokines and calcium signals between them.5. The author states, ‘virtually all the surface (cytoplasmic membrane) proteins involved in immune cells’ recognition of disease (pathogens) have been identified and named.” If this is true, then why is the immune synapse such a profound discovery?Although the proteins involved have been identified and named, their roles and how they bring about communication between immune cells has not been entirely discovered.

These discoveries, including that on the immune synapse, can be made by observing or ‘just watching’ the cells and proteins at work.6. Describe Charles Janeway’s experiment to prove that cytokine secretion can be directional; that is, that secretion can be from only one side of a cell.The team of Charles A. Janeway, Jr., at Yale University performed the following experiment in 1988: they fitted T cells tightly into the pores of a membrane, which was then immersed in a solution. A stimulant to activate T cells was added to the solution on only 1 side of the membrane.

They then detected proteins secreted by activated T cells in the solution containing the stimulant, but the proteins were absent in the stimulant-free solution on the other side of the membrane. This experiment demonstrated the ability of immune cells to secrete proteins after activation specifically in the direction of the stimulant. 7. Compare and contrast the structures of neuronal and immune synapses. The neuronal and immune synapses are similar as they both involve communication and signal transduction between two cells through the interaction and activity of specific proteins.

Neuronal and immune synapses also seem to share some common proteins, such as the Agrin protein and the Neuropilin-1 receptor. The synapse structure of both cell types forms a bull’s-eye pattern. However, they have differences too. Neuronal synapses are long-term connections; they stay in place as the neurons are stationary cells. In contrast, the immune synapse is a ‘make and break’ phenomenon. Two different immune cells that are far apart, while moving about, come in contact with each other, communicate by constructing the immune synapse, and then terminate the synapse to move away again.

In neural synapses, the synapse is held by adhesion proteins, and neurotransmitters released from one cell travel across the synapse to activate a receptor at the other end. At the immune synapse, no transmitter substances are involved, adhesion molecules maintain the synapse while proteins, such as the MHC proteins, from the two cells interact to transmit the signal. 8. Consider what you know about T cell activation by an antigen presenting dendritic cell. Outline which specific proteins must be interacting at the synapse center (green) in the top-left figure on page 56 of the article.

Antigen presenting cells (APCs) such as the dendritic cell break up the proteins from an invading organism, and present the foreign protein fragments at their surface for the immune synapse. The protein fragment (peptide) is presented within an MHC class II molecule. When a T cell comes in contact with this dendritic cell, it forms an immune synapse by interaction of its surface proteins with the MHC protein. This interaction at the synapse involves the T cell receptor binding to the MHC-peptide complex, which triggers activation of the T cell and initiation of the immune response against the specific organism.

Other essential interactions to make the synapse and activate the T cell include CD2 on the T cell binding to LFA-3 on the APC, binding of CD4 on the T cell to the APC’s MHC molecule, and binding of CD28 on the T cell to B7 protein on the APC.