Hargraves et al., identified the LE cell phenomena in bone marrow in 1948. Lupus erythromatosus is an autoimmune disease in which autoantibodies attack cell nuclei components. In lupus erythromatosus, antibodies such as LE factor, antinuclear antibodies (ANA), anti double stranded DNA (anti ds DNA), anti single stranded DNA, anti nucleoprotein, and anti nuclear glycoprotein are detected.
Lupus is a connective tissue disease, characterized by skin rash (mostly butterfly like), arthralgia, fever, renal, cardiac and vascular lesions, anemia, leucopenia and often thrombocytopenia. It involves chronic inflammation that can affect many parts of the body, including: Heart, lungs, skin, joints, blood-forming organs, kidneys, nervous system. Lupus can occur at any age however it is most common in women of child bearing age and children.
Types of Lupus Erythromatosus
Lupus erythromatosus can present as a systemic or mainly cutaneous illness. The following are examples of lupus erythromatosus types:
- Systemic lupus erythematosus (Most common and severe form)
- Drug-induced lupus erythematosus
- Neonatal lupus erythematosus
- Acute cutaneous lupus erythematosus
- Subacute cutaneous lupus erythematosus
- Discoid lupus erythematosus ( chronic cutaneous)
Formation of LE cells
The LE factor (ANF) (an immunoglobulin of the IgG, IgM or IgA class) releases an enzyme, DNAse which along with the inhibitors causes depolymerization of the nuclear chromatin of polymorphonuclear leucocytes. This depolymerized DNA of the nucleolus forms a swelling solid homogenous mass called LE body. LE body has chemotactic potential for polymorphs which results phagocytosis of itself by other non-traumatic neutrophil resulting in formation of LE cells.
The LE cell is often a neutrophil polymorph (but it can also be a monocyte or eosinophil) that has consumed the altered nucleus of another polymorph. A spherical, opaque, basophilic, homogenous mass that colors purple brown occupies the majority of the cell. The ingesting polymorph’s lobes seem to be coiled around the swallowed substance. Occasionally, a cluster of polymorphs will form a “rosette” around a changed nuclear substance.
Demonstration of LE cells
There have been several approaches of demonstrating LE cells. It appears that some level of leucocyte stress is required for effective LE cell preparation. Healthy live leucocytes are unable to respond to LE factor.
Rotating the whole blood sample with glass beads added before centrifugation to concentrate the leucocytes is an excellent way to achieve the required level of trauma.
Method Using Patient’s Blood
The Rotary Method of Zinkham and Conley
- 1 mL of heparinized patient blood is transferred to a 75 x 12mm glass tube.
- The tube is sealed with a securely fitting rubber bung after four glass beads are inserted.
- For 30 minutes, the preparation is spun at 33 rpm at room temperature before being put in a 37°C oven for 10-15 minutes.
- Transfer the contents of the tube to a Wintrobe tube and centrifuge for 10 minutes at 200g.
- Buffy coat smears are made, air-dried, fixed with methanol, then stained with Romanowsky stain as specified.
Examination of Films
- The L.E. cell is a neutrophillic leucocyte that is dilated by an intracytoplasmic homogeneous red purple body, i.e. the L.E body, and the phagocyte cell, which appears larger than normal.
- A negative report is issued after scanning the films for at least 10 minutes (counting at least 500 polymorphs). It is common to observe dead nuclei laying around; if they are abundant, they may raise suspicions, but they are not diagnostic.
A lymphocyte’s nucleus is phagocytosed by “tart cells”, which are generally monocytes. Comparatively speaking, the ingested nuclear material is highly maintained compared to the inclusion body of the LE cell. They are commonly related with leucoagglutinins and can develop in individuals who are taking medication for a variety of reasons.
Positivity in the LE cell test is highly indicative of SLE, making it a highly useful test in the diagnosis of SLE.
75 % with SLE had a positive test result.
False positive findings, however, have been recorded in individuals with lupoid hepatitis, severe and very active rheumatoid arthritis, and those on medication treatment.