Question

how can a cell mediate immunity???????????

Answer 1

Its known as cell mediated immunity, i.e immunity/protection provided by immune cells(white blood cells) against antigen/invaders, they do this by phagocytosis( cells such as macrophages and neutrophils swallows invading microbe and digests it), Natural killer(release toxins that kill invaders once they encounter them), antigen specific cytotoxic cell( such as T lymphocyte that attack only a specific type of antigen/invader and release toxins while attaching to it)..