EXPLAIN IN DETAIL THE LE CELL PHENOMENON ?
A 2 INTRODUCTION
1 This is done to diagnose Systemic lupus erythematosus.
2 Positive L E cells seen in -
A ) Systemic lupus erythematosus - These are positive in 95% of the cases.
B ) Drug induced lupus erythematosus - These are seen in 80 to 95 % of the cases.
C ) Other autoimmune diseases show LE cell in less than 20 % of the cases.
3 The lupus erythematosus (LE) cell was first described by Hargraves, Richmond, and Morton in I948.
4 LE cells were observed in the bone marrow of patients with lupus.
5 The LE cell reaction is positive in 50%-75% of individuals with acute disseminated lupus.
6 Positive reactions are also seen in rheumatoid arthritis,chronic hepatitis (lupoid), scleroderma,dermatomyositis, polyarteritis nodosa, acquired hemolytic anemia, and Hodgkin disease.
7 It may also be positive in persons taking phenylbutazone and hydralazine.
8 The ideal temperature to perform this test is 22°C, and the process may be hastened by incubation at 37°C.
9 LE cell testing is no longer used to diagnose lupus erythematosus; ANA is the criterion standard.
Pathophysiology
A ) In SLE there are various self antigens like - Nuclear histone and proteins , IgGRBCsDNA and RNAPlatelets
B ) Autoantibodies form against all above antigens…
C ) Autoantibodies form the complex as Ag+Ab which will give rise to damage by type 3 and type 2 hypersensitivity reaction.
D ) Antinuclear antibody cause damage to to nucleus which degenerates and give rise to homogeneous body called as hematoxylin body.
E ) Mature neutrophilic polymorphonuclear leukocyte, which has phagocytized a spherical, homogeneous-appearing inclusion (hematoxylin body).
F ) This the neutrophil leucocyte with presence of homogenous red purple inclusion that distend the cells and push the nucleus to one side.
G ) This inclusion is derived from nuclear material of degenerating leukocytes as the outcome of antibodies against the nuclear material.
H ) These inclusions are characteristic of lupus erythematosus, but also found in other autoimmune diseases.
PROCEDURE
1 In this , 10 mL venous blood of the patient is taken and is traumatized by a glass rod or glass beads.
2 Incubate for 20 to 30 minutes at 37 C.There will be formation of LE cells on incubation.
3 Bone marrow may be taken for this phenomenon.
4 Centrifuge the blood sample and make the slide from the buffy coat or from the white cells area.
A ) the buffy coat from venous blood is an adequate substitute.
B ) If the equipment for buffy coat is unavailable, an untreated venous blood sample is left to clot (from 20-120 minutes) and the plasma removed.
C ) The residual clot is passed through a wire mesh and centrifuged for 5 minutes to obtain a buffy coat.
D ) This buffy coat is then smeared on glass slides to search for LE cells.
The test may be performed by mixing the patient’s plasma, serum, or serous effusions as a source of LE factor with bone marrow from a donor subject.
5 Collection and Panels
Lupus erythematosus (LE) cell testing is performed using any of the following -
Heparinized bone marrow
Heparinized venous blood
Oxalated venous blood
Defibrinated venous blood
Clotted venous blood
LE factor and donor cells
6 Result - The neutrophils show intracytoplasmic inclusion pushing the homogenous degenerated nucleus to the periphery.
6 smear is considered positive when 10 or more characteristic LE cells are seen during a 15-minute search, associated with the presence of extracellular, amorphous, nuclear masses.