Foreign molecules that elicit an immune response are called a. major histocompatibility complex (MHC) molecules. b. antibodies. c. histamines. d. antigens.

Verified step by step guidance

1. Identify the role of each option in the immune system.
2. Understand that major histocompatibility complex (MHC) molecules help display antigens on cell surfaces for recognition.
3. Recognize that antibodies are proteins produced by the immune system to neutralize or destroy foreign substances.
4. Note that histamines are involved in inflammatory responses and are released by cells in response to injury and in allergic and inflammatory reactions.
5. Conclude that the molecules that specifically elicit an immune response by being recognized as foreign by the immune system are called antigens.

Key Concepts

Antigens

Antigens are foreign molecules, often proteins or polysaccharides, that trigger an immune response when detected by the body. They can originate from pathogens like bacteria and viruses, or from non-infectious sources such as pollen or transplanted tissues. The immune system recognizes these molecules as non-self, leading to the activation of immune cells and the production of antibodies.

Immune Response

The immune response is the body's defense mechanism against foreign invaders, including pathogens and antigens. It involves the recognition of antigens by immune cells, which then activate various pathways to eliminate the threat. This response can be innate (immediate and non-specific) or adaptive (specific and slower, involving memory cells for future protection).

Major Histocompatibility Complex (MHC)

The Major Histocompatibility Complex (MHC) is a set of molecules displayed on cell surfaces that play a crucial role in the immune system's ability to recognize foreign substances. MHC molecules present peptide fragments from proteins, including antigens, to T cells, facilitating the activation of the adaptive immune response. There are two main classes: MHC class I (present on all nucleated cells) and MHC class II (primarily on antigen-presenting cells).