Activation of the gene for IL-2, and eventually TH proliferation, is caused by a critical signal (along with TCR signal transduction) from ___ on the B cell and ___ on the T cell.

Correct Answer: D

Rationale: CD80 (B cell) and CD28 (T cell) provide the costimulatory signal for IL-2 production and T-helper proliferation.

Correct Answer: A

Rationale: Langerhans cells in the skin migrate to present antigens to T cells.

Correct Answer: D

Rationale: C3a and C5a are key anaphylatoxins in complement activation.

Correct Answer: A

Rationale: Diapedesis involves integrins for endothelial crossing.

Correct Answer: B

Rationale: Septic shock involves a massive cytokine release primarily from T cells in response to infection, driving the systemic inflammatory response.