True Learn- Immunology Flashcards
Acute transfusion reactions
Acute hemolytic transfusion reaction:
-Hemolysis, usually associated with ABO incompatibility
-Immediately after transfusion or several hours later (always within 24 hours)
-Fever, hypotension, tachycardia, nausea, feeling of doom, red urine, muscle pain
-Management: stopping blood transfusion. Starting hydration with crystalloid solutions, lactated ringers or normal saline, and possible diuresis with mannitol.
Uncomplicated neutropenic enterocolitis in HIV-positive patients
-Bowel rest, nasogastric suction, IV fluids, nutritional support, and empiric broad-spectrum antibiotics. Antiviral therapy against cytomegalovirus (CMV) is indicated for confirmed CMV colitis or those with CD4 count < 50 cells/μL. Antiretroviral therapy should be initiated approximately 1–2 weeks after starting anti-CMV therapy.
Diarrheal disease in individuals with HIV is frequently due to infectious enterocolitis. Current medications should be reviewed as antiretrovirals can also cause diarrhea. Stool and blood cultures are useful to identify any offending pathogens. Endoscopy may be required if the initial workup is nondiagnostic; however, caution should be used in the acute setting because of concerns for intestinal perforation. In the acute setting, a CT scan should be performed to exclude complications of enterocolitis such as perforation.
The most common cause of AIDS-related colitis is cytomegalovirus (CMV) disease and commonly results from the reactivation of a latent infection. Risk factors include CMV viremia and advanced immunosuppression, particularly with CD4 counts < 50 cells/μL. Cytomegalovirus colitis usually presents with abdominal pain and diarrhea. Stool studies may reveal viral inclusion bodies, and endoscopy may show ulcers or erosions.
Operative management is indicated in cases of perforation with free air, bowel necrosis, persistent GI bleeding despite correction of coagulopathy, or deterioration despite appropriate medical management.
A 67-year-old man received a bone marrow transplantation for a hematologic malignancy 2 months ago. He now presents with diarrhea and a diffuse maculopapular rash. What is the pathophysiology driving this process?
Graft-versus-host disease: T-cell-mediated disease
1. Damage to recipient tissue as part of the conditioning process for stem cell transplantation. This leads to translocation of microbes and activation of the innate immune system with resulting proinflammatory conditions.
- Differentiation of DONOR T-lymphocytes into Th1 and Th17 effector lineages. These Th1 and Th17 cells recognize the host as foreign and activate the JAK1, JAK2, and TLR downstream signaling pathways, then lead to release of proinflammatory cytokines such as IL-6 and interferon-gamma. These proinflammatory cytokines lead to host tissue destruction, such as by donor natural killer cells targeting MHC-I presenting cells.
3.Tissue dysregulation from these cytokines leads to the failure of the host tissue, such as the skin and gut, to properly regenerate after being destroyed.
