Specificity of the adaptive immune system and its ability to distinguish...

• Positive selection of developing T cells requires productive interaction with MHC proteins (“self”), which stimulate cell division; nonproductive interactions result in cessation of development and cell death ( apoptosis).

• Negative selection occurs next after positively selected T cells are exposed to MHC proteins that are binding self-antigens. These T cells remain in the thymus and eventually die, whereas the positively selected T cells that did not interact migrate to the lymph nodes and spleen.

• The term clonal deletion is used to describe the overall process involving positive and negative selection during T cell maturation. B cells also undergo clonal deletion in the bone marrow, but also clonal anergy (i.e., “unresponsiveness”).

T and B cells require two molecular signals for activation. The T cells migrating to the lymph nodes and spleen have not yet been exposed to nonself-antigen and are categorized as naïve. Because the thymus does not contain all possible self-antigens, there must be a safety valve for inducing unresponsiveness in T cells interacting with a self-antigen for the first time after leaving the thymus.

What textbook are these questions coming from? I could get the solutions from the manual with a little more detail.

essentials of human anatomy and physiology tenth Edition

Innate external defenses (surface barriers): Skin and mucous membranes

Innate internal defenses: Cells and chemicals in body fluids

Adaptive defenses: T and B cells

Once the surface barrier has been broken, the second line of defense, the innate internal defense system (nonspecific defense system), attempts to limit the spread of pathogens. This includes 1. Phagocytes 2. Inflammation 3. Natural killer cells 4. Fever 5. Antimicrobial proteins.

In fact, all T cells are self-reactive to a greater or lesser degree—as those with no capacity to bind to self-MHC in the thymus are not selected.

So, no.

thank you guys=DD

Solved?