C. Mammary glands can be thought of as specialized skin glands, and they are already known to secrete the antimicrobial compounds lysozyme, lactoferrin, and lactoperoxidase. Saliva flushes the mouth and esophagus with each swallow, and is replenished from the salivary glands. Calprotectin is added to the saliva by keratinocytes in the mouth. Whether this is also true of the other squamous mucosae is not known. Cilia in the nose and tracheobronchial tree transport their corresponding mucus layers posteriorly to the pharynx, where they are swallowed and dumped into the acid-bath in the stomach.
Any microbes caught in the mucus go the same route.
There is some indication that this may also be true of humans, but it is still not certain. At the extreme terminus of the tracheobronchial tree, the pulmonary surfactants, particularly surfactants A and D, add a broad-spectrum antimicrobial function. Glands in the nasal submucosa and sinuses also secrete lysozyme and lactoferrin. Tears flush the conjunctivae, with regular help from the eyelids, ultimately draining into the nose through the nasolacrimal duct, and then into the stomach by nasal ciliary action. Urine flushes the urinary tract.