Section 2: MHC & Cell-Mediated Immunity

What does MHC stand for and what does it do?

Major Histocompatibility Complex; encodes proteins that help distinguish self from non-self.

What is HLA?

Human Leukocyte Antigen – the MHC in humans, located on chromosome 6

What do Class I MHC molecules do?

Markers on all nucleated cells; basis for organ transplant typing.

What do Class II MHC molecules do?

Found on macrophages, dendritic cells, B cells; present antigens to T cells.

What do Class III MHC molecules do?

Code for complement components (not involved in self/non-self determination).

What is cell-mediated immunity?

Immunity mediated by T cells that directly attack infected cells.

What do cytotoxic T cells do?

Destroy infected host cells and foreign cells; have CD8 co-receptor.

What do helper T cells do?

Amplify innate & antibody-mediated immunity, activate macrophages, assist B cells, help activate cytotoxic T cells; have CD4 co-receptor.