Question

Which lineage of immune cells constitutes the first line of defense against an infection?

1) Lymphoid
2) Erythroid
3) Myeloid
4) All of the above
5) None of the above

Answer 1

The myeloid lineage of immune cells, which includes phagocytic cells such as neutrophils and monocytes, constitutes the first line of defense against an infection.

Step-by-step explanation:

The lineage of immune cells that constitutes the first line of defense against an infection is the myeloid lineage. This lineage includes phagocytic cells like neutrophils, eosinophils, basophils, and monocytes. These cells are primarily responsible for the innate, or nonspecific, immune response. They work rapidly to identify and destroy invasive pathogens through processes like phagocytosis, and they play a crucial role in alerting other immune cells to the presence of an infection. The innate immune response is the body's initial reaction to an infection, dealing with most bacterial invasions effectively.