1. In treating a woman for malignancy in the left breast, the surgeon removes so
ID: 3508296 • Letter: 1
Question
1. In treating a woman for malignancy in the left breast, the surgeon removes some of her axillary lymph nodes. Following surgery, the patient experiences edema of her left arm. Explain why.
2. Anti-B antibodies of a type A mother rarely affect the RBCs of a type B fetus. Yet anti-D antibodies of an Rh– woman sometimes cross the placenta and hemolyze the RBCs of an Rh+ fetus. Explain this difference based on your knowledge of the five immunoglobulin classes.
3. How does the structure of a B cell differ from that of a plasma cell? Explain how their structural difference relates to their functional difference.
Explanation / Answer
1.Acute edema can occur as a result of trauma to tissue from injury, infection, or surgical procedure. Initially, after tissue trauma, high capillary permeability or capillary rupture may lead to an overload of a healthy lymphatic system due to leakage of fluid and protein into the interstitium (tissue spaces).
3. functional
Plasma cells are able to secrete antigens immediately upon reinfection, while B cells can only do so after restimulation by specific antigens.
Affinities of plasma cells B cells receptors are higher than those of memory B cells, so that memory B cells can be formed even when affinity for its receptors are low.
structural
B cells differentiate into plasma cells that produce antibody molecules closely modelled after the receptors of the precursor B cell. Once released into the blood and lymph, these antibody molecules bind to the target antigen (foreign substance) and initiate its neutralization or destruction.
2.
During pregnancy, some of the mother's antibodies are transported across the placenta and enter the fetal circulation. This is necessary because by the time of birth, newborns have only a primitive immune system, and the continuing presence of maternal antibodies helps ensure that they survive while their immune system matures. A downside to this protection is that by targeting fetal RBCs, maternal antibodies can also cause HDN.
A major cause of HDN is an incompatibility of the Rh blood group between the mother and fetus. Most commonly, hemolytic disease is triggered by the D antigen, although other Rh antigens, such as c, C, E, and e, can also cause problems.
Pregnancies at risk of HND are those in which an Rh D-negative mother becomes pregnant with an RhD-positive child (the child having inherited the D antigen from the father). The mother's immune response to the fetal D antigen is to form antibodies against it (anti-D). These antibodies are usually of the IgG type, the type that is transported across the placenta and hence delivered to the fetal circulation.
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