Journal Article 2 Answers
1. The phenomenon of clonal selection and expansion occurs when T and B cells are activated by an invading pathogen. The leukocytes that have specific receptors for the pathogen are selected for and begin to divide via mitosis. The large number of cells that result from this expansion all have the same receptor for the pathogen that first activated the cells. Since these cells are specific for that pathogen, they are able to fight off the infection caused by the pathogen more effectively.
2. The three cell that function as antigen presenting cells (APCs) are B cells, macrophages, and dendritic cells.
3. Slow pathogens seem to be much better suited in their role of causing infection because they stay in the body …show more content…
The threshold hypothesis states that T cells may only be activated when a certain amount of antigens are located on the antigen presenting cells (APCs). Additionally, a certain level of damage to the host will cause innate immunity to respond and begin to fight back against an invading pathogen. Looking at both of these parts of the theory, it would be best to find the amount of vaccine that allows for adequate presentation on APCs and T cell activation while not going so far as to cause irreversible damage to the host. The lab director would most likely respond that the idea has some merit, but using such large doses of vaccine would cause more harm than help. Using 10, 50, and 100 times the normal dose would cause noticeable damage and activate innate immunity. It would also provide a sufficient amount of antigens to be presented to the T cells. However at these doses, the tissue damage would be so severe and the amount of pathogen so great that the immune system would have trouble managing. The lab director would possibly advocate for smaller increases in the normal dose and try to look for a middle ground between antigen presentation and host tissue damage to elicit optimal response from the body’s immune