Sarah, a forty-nine-year-old Anglo woman, visits her physician
complaining of weight loss, sweating, listlessness, and flu-like
symptoms (fever, headache, scratchy throat, generalized body ache).
After checking her history the physician notes that Sarah is
married, has four children, and no previous history of chronic
illness. Her weight has decreased 15 pounds over the past three
months and she presents with a temperature of 101 degrees F, a
slightly elevated pulse (85 beats per minute), normal blood
pressure (112/78 mm Hg), and slightly labored breathing. Sarah has
a negative family history of cardiovascular and respiratory
diseases. All of her family members are living and are free of
cardiovascular or respiratory diseases. Sarah does not smoke and is
current on all immunizations. She does report that she developed
these symptoms a few days after visiting a friend whose son was
home with a cold. After a chest X-ray and physical examination of
Sarah’s ear, nose, and throat, the physician confirms the diagnosis
and prescribes bed rest, aspirin, and a nasal decongestant. The
physician also cautions Sarah from returning to her normal
activities until she has been afebrile for a minimum of 24 hours.
Sarah’s condition continues to worsen such that a week later she
returns to her physician’s office. She has pain on the left side of
her chest, is coughing more frequently and her sputum has a yellow
color. Her respiratory rate is 32 breaths per minute and her
breathing is labored. Her blood pressure is unchanged and does not
demonstrate postural changes. Breath sounds indicate inspiratory
rales and a chest X-ray indicates a dense infiltrate within the
lungs. Physical examination reveals lymphadenopathy. The physician
suspects pneumonia and orders laboratory tests on Sarah’s blood and
sputum. The results of the sputum tests indicate the presence of
gram-positive diplococci and polymorphonucleocytes that are too
numerous to count. What concerns the physician, however, are the
results of Sarah’s blood test. Her blood tests indicate leukopenia,
anemia, and thrombocytopenia. In addition, the differential
leukocyte count indicates that the concentration of helper T cells
has decreased. The physician now suspects that Sarah has been
infected with the human immunodeficiency virus (HIV) and that she
has developed pneumonia as a result of the immune suppression. In
reviewing her history, the physician notes that Sarah has been
married for the past 30 years and does not admit to any
extramarital affairs. She has not received any blood transfusions
or blood products and does not use intravenous drugs. She is a
self-employed certified public accountant and has not visited any
countries with high incidences of HIV infection. Upon further
discussion, Sarah does mention to the physician that she and her
husband were separated a few years ago for approximately 6 months
as a result of his extramarital affair. The physician asks Sarah if
he can run another test to determine whether or not she has
contacted HIV and asks Sarah to talk to her husband about being
tested for HIV as well. The physician also begins treating Sarah
for pneumonia that has developed and asks her to return the next
day for the results of the HIV test.
The next day Sarah and her husband return to the physician’s office and the physician confirms that the enzyme-linked immunoadsorbent assay confirms that Sarah is HIV positive. The physician does mention that a second more sensitive test will be conducted to confirm this finding, however, he is doubtful that the result will indicate a false positive in the first test. Her husband admits to having numerous extramarital affairs with both women and men and consents to a blood test to determine his HIV status, which subsequently is positive. The physician then discusses the replicative cycle of HIV, the concept of a retrovirus, and treatment options with both Sarah and her husband. Sarah immediately starts on a regimen of protease inhibitors and nucleoside analogs (azidothymidine, AZT, and ddI). In addition, the physician discusses with Sarah and her husband the necessity of practicing "safe sex" even though both are HIV positive and the importance of not exposing themselves to opportunistic diseases. In addition, he mentions that some of the drugs they will be taking to minimize viral replication may cause nausea. He cautions them to take all medications as scheduled and to return to his office at the first sign of any disorder. He also reiterates that this disease can not be transferred by casual contact, but can be transferred through an exchange of body fluids (blood, semen, and vaginal secretions). Answer the following questions about this case.
1. Why was HIV not initially considered as a possible cause for the symptoms Sarah presented with?
2. Why did Sarah’s symptoms worsen and develop into pneumonia?
3. Identify the specific types of leukocytes and the function of each cell.
4. Why does HIV specifically affect one type of leukocyte?
5. Why can protease inhibitors and nucleoside analogs be used in minimizing the replication of the HIV virus?
PLEASE TYPE THE ANSWER.
Ans 1) The HIV was not considered possible cause for her symptoms initially because proper blood test was not done earlier. She has basic flu like symptoms like headache, fever, throat problem etc. with elevated pulse and labored breathing. Since she was on all immunization, HIV was not considered and until and unless the blood test was done, it was no detected that there is leukopenia along with anemia and thrombocytopenia. It was not found as she was under immune suppression and HIV was only detected when a test was done to find that there is decrease in the level of T-cells.
Ans 2) The symptoms worsened and she developed pneumonia due to immune suppression. Pneumonia is a lung disease which is caused due to the inflammation of the tiny air sacs which are present in lungs due to it being filled with fluid. This makes it difficult for one to breathe. Due to the HIV, it has caused immune suppression due to the decrease in the T-cells and hence it has put her at risk due to weakened natural defense of the body against the pathogens that are responsible for causing pneumonia.
Ans 3) The specific type of leukocyte which decreases due to HIV infection is the T- helper cell. The T-cell is an important immune cell which are able to attack and eliminate the pathogens and foreign tissues through production of cytokines. Each of the T-cell has its own T-cell receptor and it is specific for a antigen. As they encounter an antigen, they are activated and eliminate it from the system.
CD8 or cytotoxic T-cells – The cytotoxic T-cell are able to kill the target cells through the release of cytotoxic particles. The antigenic peptides are presents to these T-cells through MHC Class I. The MHC Class I interacts with cytotoxic T-cells and it activates the T-helper cells. Hence it helps in killing the cells which virally infected.
CD4 or T-helper cells – These T-helper cells activates when they are presented with antigenic peptides by MHC Class II. The MHC Class II interact with CD4 or T-helper cells and hence it helps in activating other immune cells, release cytokine and trigger the B-cells to produce antibodies.
Ans 4) The HIV specifically affect only T-helper cell or CD4+. This is because with the ability to destroy this cell, it weakens the whole immune system and hence it is not able to fight against the infection. The HIV virus tends to integrate its genome within the CD4+ and hence causes the infection and leads to the death of the CD4+ through programmed cell death. They specifically attack the CD4+ cells as they contain on their cell surface specialized protein called CD4 or cluster of differentiation 4 that recognizes the immune cells.
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