Which of the following is a characteristic feature of a leukemoid reaction?

A leukemoid reaction is characterized by a significant increase in the number of white blood cells, particularly neutrophils, in response to stress, infection, or inflammation. This physiological response mimics leukemia but is not caused by a malignancy. The absolute neutrophilia indicates that there is a marked rise in neutrophil count, usually in the range of 50,000-100,000 cells per microliter or more. This acute response is the body's way of combating an overwhelming infection or other pathological stimuli.

The presence of the Philadelphia chromosome is commonly associated with chronic myeloid leukemia (CML) and does not occur in leukemoid reactions. Low white blood cell count contradicts the definition of a leukemoid reaction since such a reaction is characterized by a high white blood cell count. Lastly, while increased lymphocyte counts can occur in certain contexts, a leukemoid reaction is specifically identified by the prominence of neutrophilia, not lymphocytosis. Therefore, the presence of absolute neutrophilia is the defining characteristic of a leukemoid reaction.