Final answer:
The presence of increased immature cells in a peripheral blood sample is known as a left shift, indicating a response such as infection or inflammation where bone marrow releases more neutrophils.
Step-by-step explanation:
The presence of increased numbers of immature cells in a peripheral blood sample is known as a left shift. This term is used to describe a change in the balance of immature to mature leukocytes in the blood in response to an infection or other disease process. When these immature cells, often called band cells, are released into the bloodstream, it signals that there is an increased demand for leukocytes to combat a threat to the body's health. A left shift typically indicates an infection or inflammation, where the bone marrow releases more neutrophils to fight off the condition, leading to an increase in immature forms.