Lesson 7-3. Demonstration of L.E. Cells
Persons having lupus erythematosus, one of the "collagen" diseases, have an abnormal plasma protein that causes swelling and breakdown of certain blood cell nuclei in vitro. This degenerated nuclear material attracts phagocytic cells, particularly segmented neutrophils, which engulf this nuclear mass. The resulting phagocyte and inclusion material is termed an "L.E." cell.
Two methods of demonstrating the L.E. cell and antinuclear antibodies are the rotary bead method and fluorescent antibody method. The rotary bead method is positive in 75-80 erythematosus. The fluorescent antibody method is positive in 95-100 patients with lupus erythematosus. The rotary bead method is presented in the next paragraph. The fluorescent antibody method requires equipment that limits its use to larger laboratories.
ROTARY BEAD METHOD
Leukocytes are broken down in vitro allowing the abnormal plasma protein to react on the altered nuclear material. Incubation enhances the nuclear deterioration and phagocytosis. Slides are prepared and examined for the peculiar "L.E." cell.
Lupus erythematosus is a chronic, sometimes fatal, disease of unknown etiology. The peculiar skin eruption across the nose and cheeks (butterfly rash) and arthritis can be accompanied by various visceral manifestations. Often the rash is not present, and diagnosis depends on demonstration of the L.E. cell. Frequently the earliest symptoms appear after intense exposure to sunlight. Leukopenia, thrombocytopenia, and an elevated sedimentation rate are some of the clinical signs of the disease.
Free masses of lysed nuclear material, with or without polymorphonuclear leukocytes clustered about them (rosette formation), are suggestive of the L.E. phenomenon. Observing "rosettes" should encourage the technician to repeat examinations and further search for the true "L.E." cells. A positive report should not be made without the identification of this cell. The inclusion body with the leukocyte is homogeneous and has no chromatin pattern. This feature distinguishes the true "L.E." cell from the "tart" cell (nucleophagocytosis). This latter cell contains an engulfed, damaged nucleus, usually that of a lymphocyte, which still contains a recognizable chromatin pattern and a distinct nuclear membrane.
These cells are seen as large polymorphonuclear (segmented) leukocytes which contain large ingested nuclear fragments in their cytoplasm.
The inclusion body is a purplish-staining, smoky, homogeneous mass of material that is so large that it usually pushes the nucleus to one side of the cell.