Immunoglobulins consisting of a mouse-derived variable region with a human-derived constant region are known as

• A. Monoclonal antibodies.
• B. Chimeric antibodies.
• C. Humanized antibodies.
• D. Fully human antibodies.

Answer: (B)

The idea being tested is how combining parts from different species in an antibody affects its function and compatibility in humans. When the variable region, which determines what the antibody binds, comes from a mouse, and the constant region, which interacts with the human immune system, comes from a human, you get a chimeric antibody. This design keeps the mouse’s binding specificity but uses a human constant region to reduce immunogenicity and improve interactions with human immune effector mechanisms. That combination is what defines a chimeric antibody, and it’s used in several therapeutic antibodies like infliximab and rituximab. In contrast, fully human antibodies have human sequences in both regions, and humanized antibodies keep mostly human variable regions with only the mouse portions limited to the binding sites themselves (CDRs). Monoclonal refers to origin from a single clone, not to the species makeup of the antibody.