140days,20weeks,5months

140days,20weeks,5months profile entries pictures affiliates thanks

welcome

We're BMT Group 1- team GLYCY
Click on the navigation bar to view the blog
Please remember to comment on the entries before you leave

profile

Gladys Chia
Chew Yu Mei
Yvonne Teo
Cornelyus Ng
Lau Leslie

13 July 2008

1:26:00 PM

Haematology

LE Cells Test

Hello! It’s been 3 weeks and I have been enjoying my attachment as much as I could. Hopefully you guys are doing well too!

Well, I am not literally attached to a standard laboratory for my 10 weeks of attachment thus I am being rotated to different sections every week. So for this week, I am attached to the Haematology section.

I will talk about one of the tests which I find it rather interesting, which is LE (Lupus Erythematosus) Cells Test. This test measures the presence of a LE factor that is found in Systemic Lupus Erythematosus (SLE) patients. LE factor is composed of IgG which is an antinuclear antibody that causes in-vitro lysis of cell nuclei of neutrophils ad phagocytosis of lysed nuclei by other viable neutrophils.

The materials required for LE cells test are 8 glass beads, 75µL of Heparin and 8ml of blood. These will be added into a 10ml plastic tube. The glass beads enables better mixing within the tube and Heparin acts as an anti-coagulant. Venous blood is collected and immediate testing have to take place so that the entire test will be accurate, thus the time of blood collection have to be noted properly. Usually, we would prefer samples to reach the laboratory less than 15 minutes after the blood is taken.

The method of this test is rather long, as it takes up to 1½ hours.
1. After the blood collection, let the tube stand for 30 minutes.
2. Traumatize the cells by placing the tube on the suspension mixer, revolving at 33 rpm for 30 minutes.
3. Stand the tube for another 30 minutes.
4. Centrifuge the tube at 3000 rpm for 10 minutes.
5. As the red blood cells and plasma are separated, slightly mix a little of red blood cells with the Buffy Coat and drip a drop onto the glass slide.
*Buffy Coat is found between the red blood cells and plasma, whereby it contains most of the white blood cells and platelets.*
6. Make several smears from the sample and stain them using Aerospray (uses Eosin stain and Thiazin Stain)
7. Observe the smears under microscopy with emulsion oil at 40x magnification. Slides have to be examined at least 10 minutes before a negative report is made.

This is a picture of the Aerospray machine:

The inner portion of the machine, whereby it have to be balanced on both sides and a cover have to be placed properly to begin the staining. Acts similarly like a centrifuge.

Under microscopy, the smears will show a lot of white blood cells and platelets due to the Buffy Coat. As this test has to look out for the phagocytosis of neutrophils, thus the buffy coat is needed. Neutrophils are observed to be a homogenous mass stained as pale purple. The nuclei of the ingested leucocytes are displaced to one side of the cell with a huge amount of cytoplasm in the center. These have to be counted manually and a positive result has to be reported as Number of LE cells/1000 neutrophils. As for a negative result, it has to be reported as LE cells: Negative. For this test, as long as there is a presence of one LE cell, it indicates that there is autoimmune disease in the patient. Here is a picture of how the LE cells look like under microscopy:

Picture taken from: Miwa, S. (1998). Atlas of Blood Cells. pg68. Bunkodo Co. Ltd

Picture taken from: Miwa, S. (1998). Atlas of Blood Cells. pg68. Bunkodo Co. Ltd

So far, there is no treatment for SLE. Thus, the patient may be able to live up to a few years before passing on. This test may not be commonly practiced in most of the laboratories nowadays, but for the laboratory I am attached to, we do have such samples at least once per week. Hopefully this information is useful! Cheers! (:

Yvonne Teo

21 comments