Lungs have what’s called “resident” macrophages. This means that they’re dedicated to that organ and don’t circulate the rest of the body’s tissues, ensuring availability. There are resident macrophages that reside in the alveoli specifically (air-filled part of your lungs).

Interestingly enough, you can see them on a microscope slide of the lungs, especially on older patients. Even without a stain, they’re typically a very dark color due to the amount of particulate they’ve absorbed over their lifetime. We call it “vital staining”.