B-cell depleting antibodies — MCQs

A researcher is studying the effects of various substances on mature B-cells. She observes that while most substances are only able to promote the production of antibodies when the B-cells are co-cultured with T-cells, a small subset of substances are able to trigger antibody production even in the absence of T-cells. She decides to test these substances that stimulate B-cells alone by injecting them into model organisms. She then analyzes the characteristics of the response that is triggered by these substances. Which of the following correctly describes how the immune response triggered by the B-cell-alone-substances compares with that triggered by substances that also require T-cells?

A 33-year-old woman with a history of multiple sclerosis is brought to the physician because of dizziness, urinary incontinence, loss of vision in her right eye, and numbness and weakness of the left leg. She has had recurrent episodes of neurological symptoms despite several changes in her medication regimen. An MRI of the brain shows several new enhancing lesions in the periventricular white matter and the brainstem. Treatment with a drug that binds to CD52 is initiated. Which of the following agents was most likely prescribed?

A 61-year-old man presents to the emergency department with new-onset dizziness. He reports associated symptoms of confusion, headaches, and loss of coordination. The patient’s wife also mentions he has had recent frequent nosebleeds. Physical examination demonstrates a double vision. Routine blood work is significant for a slightly reduced platelet count. A noncontrast CT of the head is normal. A serum protein electrophoresis is performed and shows an elevated IgM spike. The consulting hematologist strongly suspects Waldenström’s macroglobulinemia. Which of the following is the best course of treatment for this patient?

A 44-year-old man is brought to the emergency department by his daughter for a 1-week history of right leg weakness, unsteady gait, and multiple falls. During the past 6 months, he has become more forgetful and has sometimes lost his way along familiar routes. He has been having difficulties operating simple kitchen appliances such as the dishwasher and the coffee maker. He has recently become increasingly paranoid, agitated, and restless. He has HIV, hypertension, and type 2 diabetes mellitus. His last visit to a physician was more than 2 years ago, and he has been noncompliant with his medications. His temperature is 37.2 °C (99.0 °F), blood pressure is 152/68 mm Hg, pulse is 98/min, and respirations are 14/min. He is somnolent and slightly confused. He is oriented to person, but not place or time. There is mild lymphadenopathy in the cervical, axillary, and inguinal areas. Neurological examination shows right lower extremity weakness with normal tone and no other focal deficits. Laboratory studies show: Hemoglobin 9.2 g/dL Leukocyte count 3600/mm3 Platelet count 140,000/mm3 CD4+ count 56/μL HIV viral load > 100,000 copies/mL Serum Cryptococcal antigen negative Toxoplasma gondii IgG positive An MRI of the brain shows disseminated, nonenhancing white matter lesions with no mass effect. Which of the following is the most likely diagnosis?

A 71-year-old man comes to the physician for routine health maintenance examination. He feels well. He has hypertension and gastroesophageal reflux disease. Current medications include metoprolol and pantoprazole. He does not smoke or drink alcohol. Temperature is 37.3°C (99.1°F), pulse is 75/min, and blood pressure 135/87 mm Hg. Examination shows no abnormalities. Laboratory studies show: Hematocrit 43% Leukocyte count 32,000/mm3 Segmented neutrophils 22% Basophils 1% Eosinophils 2% Lymphocytes 74% Monocytes 1% Platelet count 190,000/mm3 Blood smear shows small, mature lymphocytes and several smudge cells. Immunophenotypic analysis with flow cytometry shows B-cells that express CD19, CD20 and CD23. Which of the following is the most appropriate next step in management?

A 38-year-old woman comes to the physician for a follow-up examination. Two years ago, she was diagnosed with multiple sclerosis. Three weeks ago, she was admitted and treated for right lower leg weakness with high-dose methylprednisone for 5 days. She has had 4 exacerbations over the past 6 months. Current medications include interferon beta and a multivitamin. Her temperature is 37°C (98.6°F), pulse is 90/min, and blood pressure is 116/74 mm Hg. Examination shows pallor of the right optic disk. Neurologic examination shows no focal findings. She is anxious about the number of exacerbations and repeated hospitalizations. She is counseled about the second-line treatment options available to her. She consents to treatment with natalizumab. However, she has read online about its adverse effects and is concerned. This patient is at increased risk for which of the following complications?

A 28-year-old woman has a follow-up visit with her physician. She was diagnosed with allergic rhinitis and bronchial asthma at 11 years of age. Her regular controller medications include daily high-dose inhaled corticosteroids and montelukast, but she still needs to use a rescue inhaler 3–4 times a week following exercise. She also becomes breathless with moderate exertion. After a thorough evaluation, the physician explains that her medication dosages need to be increased. She declines taking oral corticosteroids daily due to concerns about side effects. The physician prescribes omalizumab, which is administered subcutaneously every 3 weeks. Which of the following best explains the mechanism of action of the new medication that has been added to the controller medications?

A biology student is studying apoptosis pathways. One of the experiments conducted involves the binding of a ligand to a CD95 receptor. A defect of this pathway will most likely cause which of the conditions listed below?

A patient is infected with a pathogen and produces many antibodies to many antigens associated with that pathogen via Th cell-activated B cells. This takes place in the germinal center of the lymphoid tissues. If the same patient is later re-infected with the same pathogen, the immune system will respond with a much stronger response, producing antibodies with greater specificity for that pathogen in a shorter amount of time. What is the term for this process that allows the B cells to produce antibodies specific to that antigen?

A scientist is studying the process of thymus-dependent B cell activation in humans. He observes that, after bacterial infections, the germinal centers of secondary lymphoid organs become highly metabolically active. After subsequent reinfection with the same pathogen, the organism is able to produce immunoglobulins at a much faster pace. Which of the following processes is likely taking place in the germinal centers at the beginning of an infection?