Neutrophils in blood

Age dynamics and leukocyte crossovers

The neutrophil count changes as a child grows. For a proper evaluation of lab results, it is necessary to keep in mind the physiological crossovers of the leukocyte formula:

• At birth: neutrophils predominate, accounting for 60–65% of all leukocytes.
• 5 days of life (first crossover): the neutrophil count decreases while the lymphocyte count increases, and their ratio equalizes.
• Under 5 years: lymphocytes predominate in the blood (50–60%), and the neutrophil level remains relatively low.
• 5 years (second crossover): the parameters intersect again and become equal.
• Over 5 years: the adult blood picture is established.

In adults, the relative content of all measured neutrophils normally ranges from 50–80% (57–71% according to some classifications). An increase in the number of these cells is called neutrophilia, and a decrease is called neutropenia.

Nuclear shift of neutrophils

Nuclear shift refers to a change in the ratio of mature to immature cell forms.

Shift to the left is an increase in the pool of young, band neutrophils or the release of myelocytes, promyelocytes, and myeloblasts into the blood. This is a sign of leukocyte rejuvenation due to severe bone marrow stimulation. To assess the shift, the Schilling index is used—the sum of all immature cells divided by the number of segmented neutrophils. Normally, it is 1/16 – 1/20. With a shift to the left, the index approaches unity and higher.

Types of shift to the left:

1. Simple (hyporegenerative): only the number of band forms increases. In moderate leukocytosis, it indicates a mild infection and a good immune response.
2. Regenerative: the level of metamyelocytes (young forms) increases.
3. Hyperregenerative: myelocytes appear in the peripheral blood. It develops in severe septic and purulent conditions.
4. Leukemoid: release of myeloblasts and promyelocytes. The picture resembles myeloid leukemia.

Important: an extremely unfavorable prognostic sign is the combination of a leukemoid reaction with neutropenia and leukopenia. This indicates a sharp drop in the body's resistance.

Shift to the right is characterized by cell aging. The Schilling index in this case approaches zero.

Morphology and degenerative changes

Neutrophils belong to the myeloid lineage. Their cytoplasm contains abundant fine pinkish-purple granulation.

Young, immature granulocytes (from myeloblast to metamyelocyte) are large in size and have a large, pale nucleus. In early forms, the nuclei contain nucleoli. Mature granulocytes are smaller; their dark nuclei lack nucleoli and look like curved bands or segments connected by thin filaments.

In severe intoxications, endogenous poisonings, and severe pneumonias, a degenerative shift occurs—an increase in the number of immature cells combined with their damage:

• Toxic granulation: large, coarse basophilic granules. They arise due to the coagulation of cytoplasmic protein under the influence of toxins.
• Cytoplasmic vacuolization and nuclear pyknosis.
• Hypersegmentation: the appearance of nuclei with 6 or more segments. It reflects a shift of the formula to the right (found in leukemias and B12-deficiency anemia).

The appearance of degenerative forms along with leukopenia indicates severe suppression of bone marrow function.

Class and exam questions

What else to study on this topic

• Calculation of absolute leukocyte content by proportion
• Leukocyte intoxication index (Kalf-Kalif formula)
• Morphological differences between eosinophils and basophils
• Clinical significance of absolute and relative lymphocytosis
• Evaluation of the monocyte lineage in infections

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.