From the Guidelines
Reactive lymphocytes in peripheral blood smears can exhibit a range of morphological changes, including increased cell size, abundant and deeply basophilic cytoplasm, cytoplasmic vacuolation, and irregular cytoplasmic borders, as well as nuclear changes such as an open chromatin pattern and visible nucleoli. These changes are indicative of lymphocyte activation in response to antigenic stimulation. According to the most recent and highest quality study available, which is not directly provided in the given evidence but based on general medical knowledge, reactive lymphocytes can display several characteristic features. These include:
- Increased cell size, typically 1.5-3 times normal
- Abundant cytoplasm that is often deeply basophilic
- Cytoplasmic vacuolation
- Irregular cytoplasmic borders that may appear to mold around adjacent red blood cells
- A nucleus that remains round to oval but may become indented or kidney-shaped
- A more open, less condensed chromatin pattern than normal lymphocytes
- Visible nucleoli, which are not typically seen in normal circulating lymphocytes
- Peripheral basophilia with a paler perinuclear zone (Golgi zone)
The provided study 1 discusses chronic lymphocytic leukemia (CLL) and its diagnostic criteria, including the presence of ≥5000 B lymphocytes/µl in the peripheral blood and the characteristic morphology of CLL cells, which are small, mature lymphocytes with a narrow border of cytoplasm and a dense nucleus lacking discernable nucleoli. However, this information is not directly relevant to the morphological changes in reactive lymphocytes. The morphological changes in reactive lymphocytes are more closely related to their activation state and the underlying cause of the immune response, such as viral infections, other infections, drug reactions, and various inflammatory conditions.
From the Research
Morphological Changes in Reactive Lymphocytes
Reactive lymphocytes can exhibit various morphological changes when observed in a peripheral blood smear. These changes can include:
- Reactive forms
- Downey forms
- Increased large granular lymphocytes
- Plasmacytoid cells 2 These changes can be seen in response to various stimuli, such as infection or inflammation.
Characterization of Reactive Lymphocytes
Reactive lymphocytes can be characterized using image-based recognition systems, which can extract features such as geometry, color, and texture to distinguish between normal, reactive, and abnormal lymphocytes 3. This can be useful in automatic screening of peripheral blood smears to identify abnormal lymphoid cells.
Assessment of Peripheral Blood Lymphocytosis
Peripheral blood lymphocytosis can be assessed using thresholds for absolute lymphocyte count (ALC) and age to identify cases that require review by pathologists 4. This can help reduce laboratory workload without compromising patient care.
Infection Risk in Lymphoproliferative Disorders
Patients with lymphoproliferative disorders treated with new targeted drugs are at risk of severe infections, particularly bacterial and viral infections 5, 6. The risk of infection can be increased by factors such as severe lymphopenia, combined targeted treatment, and previous rituximab treatment. Antimicrobial prophylaxis should be considered in selected cases with specific risk factors for infection.