A patient with a severe bacterial infection has elevated levels of C-reactive protein (CRP) in their blood. Which of the following functions does CRP primarily serve during the acute phase response?

Correct Answer: B

Rationale: During the acute phase response, C-reactive protein (CRP) primarily serves to activate the complement system. CRP binds to phosphocholine on the surface of pathogens, allowing for the activation of the classical pathway of the complement system. This leads to the recruitment of immune cells, opsonization of pathogens, and enhancement of phagocytosis. The activation of the complement system by CRP plays a crucial role in the host defense against infections, aiding in the elimination of pathogens and the resolution of inflammation.

Correct Answer: A

Rationale: The development of autoantibodies such as antinuclear antibodies (ANA) and anti-double-stranded DNA (anti-dsDNA) antibodies in systemic lupus erythematosus (SLE) is primarily attributed to a loss of self-tolerance. Self-tolerance refers to the immune system's ability to recognize and differentiate self-antigens from foreign antigens. In individuals with SLE, there is a breakdown in immune tolerance mechanisms, leading to the production of autoantibodies against self-antigens like nuclear components (e.g., DNA, RNA, histones). This loss of self-tolerance results in the immune system targeting and attacking its tissues, leading to the systemic inflammation and tissue damage characteristic of SLE. The presence of elevated levels of ANA and anti-dsDNA antibodies in this patient suggests an autoimmune response against nuclear material, further supporting the role of self-tolerance breakdown in SLE

Correct Answer: B

Rationale: The most effective treatment for addressing the underlying pathophysiology of cystic fibrosis (CF) and preventing disease progression is the use of mucolytic agents, such as dornase alfa. CF is a genetic disorder that leads to the production of thick, sticky mucus in the respiratory tract. This mucus buildup can obstruct airways, lead to recurrent infections, and contribute to pulmonary exacerbations. Mucolytic agents work by reducing the viscosity of the mucus, making it easier to clear from the airways. This helps to improve lung function, reduce the frequency of exacerbations, and slow down disease progression in CF patients. Inhaled corticosteroids may be used for managing airway inflammation, but they do not target the underlying mucus production in CF. Antibiotic therapy is important for treating respiratory infections in CF patients, but it does not address the primary

Correct Answer: A

Rationale: In a patient with suspected pulmonary TB, the most appropriate diagnostic test for confirming the diagnosis is the sputum acid-fast bacilli (AFB) smear and culture. This test involves examining sputum samples under the microscope for the presence of acid-fast bacilli, which are characteristic of Mycobacterium tuberculosis, the bacteria that causes TB. Additionally, culturing the sputum allows for the bacteria to grow in a controlled environment, further confirming the diagnosis. In the given scenario, the patient's symptoms (cough, weight loss, night sweats, hemoptysis), along with chest X-ray findings of upper lobe infiltrates and cavitation, are highly suggestive of pulmonary TB. Therefore, performing a sputum AFB smear and culture is crucial for definitive diagnosis and initiation of appropriate treatment. The other options (Tuberculin skin test, Interferon

Correct Answer: A

Rationale: The patient's presentation with fatigue, pallor, dyspnea on exertion, low hemoglobin level, decreased MCV, and decreased MCHC are all consistent with iron deficiency anemia. Iron deficiency anemia is the most common type of anemia and occurs when there is insufficient iron available for hemoglobin production. The low hemoglobin level results in symptoms such as fatigue and pallor, while the decreased MCV and MCHC indicate microcytic and hypochromic red blood cells, respectively, which are characteristic of iron deficiency anemia. Vitamin B12 deficiency anemia and thalassemia typically present with a different pattern of laboratory findings and clinical manifestations. Sickle cell anemia is characterized by sickle-shaped red blood cells due to a genetic mutation, and the laboratory findings in sickle cell anemia are different from those seen in the patient described in this scenario.