How well do you know the body's defense mechanisms?

Which type of cells form a mechanical barrier against microbes at the interfaces between the body and the external environment?

What is the name of the substance produced by mucosal epithelial cells that prevents most microbes from interacting with and infecting or getting through the epithelia?

What are the names of the antimicrobial peptides produced by epithelial cells that kill bacteria and some viruses by disrupting their outer membranes?

What are the lymphocytes called that belong to the T cell lineage but express antigen receptors of limited diversity, and are found in the epithelia?

What is the name of the lipid structures that intraepithelial T lymphocytes often recognize and react against in infectious agents that attempt to breach the epithelia?