During an acute inflammatory response which of the following is the first event

Correct Answer: B

Rationale: The correct answer is B because upregulation of endothelial adhesion molecules is the first event during an acute inflammatory response. This event facilitates the initial recruitment of leukocytes, including neutrophils, to the site of inflammation. Extravasation of neutrophils (choice A) occurs after adhesion molecules are upregulated. Secretion of opsonins (choice C) and phagocytosis (choice D) occur later in the inflammatory response process after the neutrophils have been recruited to the site of inflammation.

Correct Answer: D

Rationale: Step 1: Adjuvants like AS03 induce danger signals by activating innate immunity, enhancing the response to the vaccine. Step 2: Adjuvants generally boost the innate immune response by increasing antigen presentation and cytokine production. Step 3: Adjuvants create a slower release of antigen, forming an antigen depot which prolongs immune stimulation. Summary: Choice D is correct because adjuvants like AS03 do induce danger signals, boost the innate immune response, and create a slower release of antigen, leading to enhanced vaccine efficacy. Choices A, B, and C are incorrect as they do not encompass all the effects of adjuvants in flu vaccines.

Correct Answer: C

Rationale: The correct answer is C because immunoglobulin gene rearrangement creates a complete V exon in the B cell DNA. This process happens during B cell development, where segments of V, D, and J gene regions are rearranged to form a functional immunoglobulin gene. This rearrangement occurs before transcription, so option A is incorrect. Option B is incorrect because the V exon is not complete in the germline DNA, but rather created through rearrangement in the B cell DNA. Option D is incorrect as it combines two incorrect statements.

Correct Answer: C

Rationale: The correct answer is C: Macrophages, B cells, dendritic cells. Professional antigen-presenting cells are specialized immune cells that effectively present antigens to T cells. Macrophages, B cells, and dendritic cells are considered professional APCs because they express major histocompatibility complex (MHC) molecules and co-stimulatory molecules, allowing them to effectively activate T cells. Neutrophils and epithelial cells are not considered professional APCs as they have limited ability to present antigens to T cells. B cells and T cells are not APCs themselves, but B cells can act as APCs when they present antigens to T cells in the context of an immune response.

Correct Answer: D

Rationale: The correct answer is D because the adaptive immune response relies on the initiation by the innate immune response (A), involves both humoral (antibody production) and cell-mediated (T cell activation) responses (B), and produces cytokines that can modulate the activity of innate immune cells like macrophages (C). Therefore, all of the statements are true regarding the adaptive immune response, making option D the correct choice.