Antibody A molecule that links to specific other molecules, used, for example, to deactivate or mark pathogens for destruction.
Depression An illness marked by sad mood, and loss of energy and interest in life.
Correlation A statistical finding that two events are linked in some way; a correlation suggests but does not prove that one event causes the other.
Lymphocyte A white blood cell that is part of the immune system.
Metastatic A cancer that has moved from its original site in the body.
Natural killer cells A white blood cell that attacks and kills cancers and pathogens.
Receptor A molecule on a cell surface that is designed to attract and hold only specific molecules in a system that sends messages into cells.
