Autoimmune mechanisms — MCQs

A 47-year-old woman comes to the physician because of progressive pain and stiffness in her hands and wrists for the past several months. Her hands are stiff in the morning; the stiffness improves as she starts her chores. Physical examination shows bilateral swelling and tenderness of the wrists, metacarpophalangeal joints, and proximal interphalangeal joints. Her range of motion is limited by pain. Laboratory studies show an increased erythrocyte sedimentation rate. This patient's condition is most likely associated with which of the following findings?

A 9-year-old boy is brought to your office due to nausea and vomiting. He had 4 episodes of non-bloody and non-bilious emesis over the last 24 hours. He denies any diarrhea or changes in his diet; however, his best friend at school recently had viral gastroenteritis and his mother is concerned that he has the same bug. She notes that he has been drinking more water than usual and wet his bed twice over the last two weeks. He is otherwise healthy and is not taking any medications. On physical exam his temperature is 99°F (37.2°C), blood pressure is 100/70 mmHg, pulse is 112/min, respirations are 26/min, and pulse oximetry is 99% on room air. He has lost 10 pounds since his previous visit 6 months ago. There is diffuse, mild abdominal tenderness to palpation. The most likely disease process responsible for this patient's symptoms is associated with which of the following?

A 42-year-old woman presents complaining of pain in her hands. She reports that the pain is in both hands, and that it is usually worse in the morning. She reports that her hands are also stiff in the morning, but that this gradually improves throughout the morning. She notes, however, that her symptoms seem to be getting worse over the last three months. What is the most likely pathogenesis of her disease process?

A 55-year-old man with a history of fatigue and exertional dyspnea presents to the urgent care clinic following an acute upper respiratory illness. On physical examination, his pulses are bounding, his complexion is very pale, and scleral icterus is apparent. The spleen is moderately enlarged. Oxygen saturation is 79% at rest, with a new oxygen requirement of 9 L by a non-rebreather mask. Laboratory analysis results show a hemoglobin level of 6.8 g/dL. Of the following options, which hypersensitivity reaction does this condition represent?

A 53-year-old woman presents to her primary care physician with joint pain. She reports a 6-month history of progressive pain in her hands that is worse around her knuckles. The pain is symmetric bilaterally and seems to improve after she starts working in the morning at her job in a local grocery store. She has also lost 10 pounds over the past 6 months despite no changes in her diet or exercise regimen. Her past medical history is notable for seasonal allergies, hypertension, and intermittent constipation. She takes losartan and a laxative as needed. She had adolescent idiopathic scoliosis as a child and underwent a spinal fusion at the age of 14. She does not smoke or drink alcohol. Her temperature is 98.6°F (37°C), blood pressure is 135/75 mmHg, pulse is 92/min, and respirations are 16/min. On examination, she appears well and is appropriately interactive. Strength is 5/5 and sensation to light touch is intact in the bilateral upper and lower extremities. An examination of her hands demonstrates symmetric swelling of the metacarpophalangeal joints bilaterally. This patient's condition is most strongly characterized by which of the following?

A 7-year-old boy presents to an urgent care clinic from his friend’s birthday party after experiencing trouble breathing. His father explains that the patient had eaten peanut butter at the party, and soon after, he developed facial flushing and began scratching his face and neck. This has never happened before but his father says that they have avoided peanuts and peanut butter in the past because they were worried about their son having an allergic reaction. The patient has no significant medical history and takes no medications. His blood pressure is 94/62 mm Hg, heart rate is 125/min, and respiratory rate is 22/min. On physical examination, his lips are edematous and he has severe audible stridor. Of the following, which type of hypersensitivity reaction is this patient experiencing?

A 31-year-old woman presents to her primary care provider to discuss the results from a previous urine analysis. She has no new complaints and feels well. Past medical history is significant for systemic lupus erythematosus. She was diagnosed 5 years ago and takes hydroxychloroquine every day and prednisone when her condition flares. Her previous urine analysis shows elevated protein levels (4+) and blood (3+). The urine sediment contained red blood cells (6 RBCs/high-power field). The treating physician would like to perform a renal biopsy to rule out lupus nephritis. What type of hypersensitivity is suggestive of lupus nephritis?

A 12-year-old child is exposed to pollen while playing outside. The allergen stimulates TH2 cells of his immune system to secrete a factor that leads to B-cell class switching to IgE. What factor is secreted by the TH2 cell?

A 33-year-old man comes into the urgent care clinic with an intensely itchy rash on the bilateral mid-lower extremities, with a fine linear demarcation approximately an inch above his socks. The rash is arranged in streaks of erythema with superimposed vesicular lesions. The patient states that he recently began hiking in the woods behind his house, but he denies any local chemical exposures to his lower extremities. His vital signs include: blood pressure of 127/76, heart rate of 82/min, and respiratory rate of 12/min. Of the following options, which is the mechanism of his reaction?

A 43-year-old man presents to the emergency department following a work-related accident in which both arms were amputated. The patient lost a substantial amount of blood prior to arrival, and his bleeding is difficult to control due to arterial damage and wound contamination with debris. His complete blood count (CBC) is significant for a hemoglobin (Hgb) level of 5.3 g/dL. The trauma surgery resident initiates the massive transfusion protocol and orders whole blood, O negative, which she explains is the universal donor. The patient receives 6 units of O negative blood prior to admission. He subsequently develops fever, chills, hematuria, and pulmonary edema. Several hours later, the patient goes into hemodynamic shock requiring the emergent administration of vasopressors. Of the following options, which hypersensitivity reaction occurred?