Antihistamines are most likely to interfere directly with which of the following nonspecific immune ...

Answer to q. 1

B; Histamines act on capillaries, making them leaky. This causes a runny nose and teary eyes, which tend to wash out viral particles. It also permits leaking of fluid into infected tissues, and the fluid will bring with it phagocytes and, eventually, antibodies. Constriction of bronchioles and increase of mucus secretion (choices a and c) are the results of prostaglandin stimulus. Antibody production (choice d) is part of the specific immune response. Histamine is not thought to directly activate killer cells (choice e).

Answer to q. 2

E; The nonspecific immune system is primed to respond immediately to various categories of infective agents. The specific, involving specific recognition molecules, takes longer to respond, but is specific to each agent, and retains memory of previous exposure, which forms the basis for the effectiveness of vaccines.

Good timing, thanks!