Cells of the innate immune system and cells of the adaptive immune system differ in that only the latter:

Question

Quizplus · Accepted Answer

11ecba2d_1033_fdab_a3bf_73028dd18834_MD0008_00 The immune system, divided into innate and adaptive immunity, comprises several types of immune cells, all of which are produced from bone marrow stem cells (Choice B). These immune cells monitor the body for foreign pathogens by circulating throughout the blood and lymph. Cells of the innate immune system rapidly and nonspecifically mount immune responses against foreign antigens. Innate immune cells can respond to many types of foreign antigens and cellular stress signals to mount immediate responses against invading pathogens. In contrast, cells of the adaptive immune system recognize and bind only one type of foreign antigen, mounting specialized immune responses against invading pathogens. Adaptive immune cells must be activated prior to mounting an immune response, a process that may take several days (Choice A). These adaptive immune cells include: T lymphocytes, which recognize and bind specific foreign antigens displayed by specialized surface proteins called major histocompatibility complex (MHC) proteins on other cells. T lymphocytes include both helper T cells and cytotoxic T cells. B lymphocytes, which are activated by binding and phagocytizing foreign antigens. Within B lymphocytes, these antigens are broken down and MHC proteins bind the antigen fragments, transporting them to the cell surface. Generally, helper T cells bind foreign antigens presented by B lymphocyte MHC proteins and release signaling molecules that stimulate B lymphocytes to divide and differentiate into antibody-secreting plasma cells and memory B cells, which can respond more rapidly in the event of a future infection. (Choice D) Antigen-presenting MHC proteins are expressed on the surface of all nucleated cells (ie, except red blood cells). Accordingly, cells of both the innate and adaptive immune system express MHC proteins. Educational objective: Innate immune cells rapidly and nonspecifically mount immune responses against foreign antigens. In contrast, adaptive immune cells recognize specific foreign antigens, mounting specialized immune responses against invading pathogens. In addition, adaptive immune cells may take several days to mount an immune response whereas innate immune cells can respond immediately.

Cells of the Innate Immune System and Cells of the Adaptive