Which of the following body system are involved in the first line of defense of the immune system against infection?

The first line of defense (or outside defense system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called necrophiliacs.

Necrophiliacs/Neutrophils.

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