What type of immune response is primarily due to CD8+ T cells?

The correct answer is the cell-mediated response because CD8+ T cells, also known as cytotoxic T lymphocytes, are crucial components of this type of immune response. CD8+ T cells play a significant role in directly killing infected cells, particularly those infected with viruses or transformed by cancer. They recognize antigens presented by major histocompatibility complex (MHC) class I molecules on the surface of these cells, leading to their activation and subsequent destruction of the infected or abnormal cells.

The cell-mediated response is an essential part of the adaptive immune system, distinct from the humoral response, which involves antibodies produced by B cells. While humoral immunity is important for neutralizing pathogens in body fluids, the cell-mediated response focuses on targeting and eliminating intracellular pathogens and tumor cells directly.

The other response options do not relate to CD8+ T cells: the innate response involves non-specific defense mechanisms that do not involve T cells and primarily includes barriers like skin and immune cells such as macrophages and neutrophils. The complement response refers to a group of proteins that enhance the ability to clear microbes and damaged cells, promote inflammation, and attack pathogen cell membranes, which is separate from the activities of T cells.