Reactive lymphocyte

Reactive Lymphocyte

Close-up of a reactive lymphocyte.

A reactive lymphocyte is a type of lymphocyte that has been activated in response to an antigen. These cells are typically larger than normal lymphocytes and exhibit a variety of morphological changes. Reactive lymphocytes are often seen in the context of viral infections, such as infectious mononucleosis, and other immune responses.

Morphology

File:Atypical lcyte.jpg

Atypical lymphocyte showing characteristic features.

Reactive lymphocytes are characterized by their increased size, often measuring 12-30 micrometers in diameter. They have abundant cytoplasm, which can appear basophilic and may contain vacuoles. The nucleus of a reactive lymphocyte is often irregularly shaped, with a coarse chromatin pattern. The nucleoli may be prominent, and the nuclear membrane can be indented or folded.

Causes

Reactive lymphocytes are typically seen in response to:

• Viral infections such as Epstein-Barr virus (EBV), cytomegalovirus (CMV), and HIV.
• Bacterial infections like tuberculosis and brucellosis.
• Autoimmune disorders such as systemic lupus erythematosus (SLE).
• Drug reactions and allergic reactions.

Clinical Significance

The presence of reactive lymphocytes in a blood smear can be an important diagnostic clue. In the context of infectious mononucleosis, for example, the presence of atypical lymphocytes is a hallmark finding. Reactive lymphocytes can also be seen in other conditions, and their presence should be interpreted in conjunction with clinical findings and other laboratory tests.

Related Pages

• Lymphocyte
• Infectious mononucleosis
• Epstein-Barr virus
• Cytomegalovirus
• Immune system