Download Antibody Screen by Gel Card Test System

ANTIBODY SCREEN BY GEL CARD TEST SYSTEM
PRINCIPLE
The antibody screen test is used in the detection of unexpected blood group antibodies. In this test, the reagent
red blood cells in a hypotonic buffered saline solution are combined with patient serum/plasma to allow
antigen/antibody interaction in the upper chamber of the microtube. This results in promoting antibody uptake.
The detection of this antibody occurs when the sensitized red blood cells react with the Anti-IgG gel in the
microtube during centrifugation.
SPECIMEN
Draw one EDTA tube. Spin for 5 minutes at 3400 rpm.
REAGENTS
Antibody screen cells comprised of two vial of human red blood cells (3%)
MTS Diluent 2, a hypotonic buffered saline solution
MTS Anti-IgG Card, Anti-IgG (Rabbit) suspended in gel
QUALITY CONTROL
To recognize reagent deterioration, the reagents must be tested daily with appropriate controls. See Quality
Control procedure in this manual. MTS Diluent 2 must be visually checked to ensure that the liquid is not
discolored, turbid, or showing any signs of bacterial contamination. Also a known positive and negative cell should
be tested by the antibody screen procedure with the MTS gel card.
PROCEDURE
1. Label the MTS IgG card with the appropriate patient identification and test information (I and II)
2. Remove the foil seal from the card.
3. Using an appropriate pipette, add 50 uL of each antibody screen red blood cell suspension to the correct
microtube.
4. Using an appropriate pipette, add 25 uL of plasma to the correct microtube(s).
5. Incubate at 37 degrees C for 15 minutes.
6. Centrifuge the gel card for 10 minutes.
7. Read the front and the back of each microtube macroscopically and record reactions as described in the
INTERPRETATION section below.
INTERPRETATION
• Negative – a complete sedimentation of all red cells on the bottom of the microtube.
• Strong positive – cells remain suspended on the top of the gel.
• Weak positive – cells are dispersed throughout the gel.
• Mixed cell reactions may be recognized as a layer of positive cells at the top of the gel accompanied by a button
of negative cells at the bottom of the microtube.
• Clots, particles or other artifacts may cause some cells to be entrapped at the top of the gel which may cause an
anomalous result in a negative test.
• A few cells may form a button at the bottom of the microtube in some positive reactions.
• See ID-Micro Typing System Interpretation Guide for additional grading information.
1
RESULTS
Hemolysis or agglutination of any of the screening cells in the gel card indicates the presence of an antibody
directed against the corresponding antigen which is present of the screening cells.
No agglutination or hemolysis of the screening cells in the gel card is a negative test result and indicates the
absence of an antigen/antibody reaction.
All positive screens must be confirmed with an antibody identification. (See appropriate procedure in this
manual).
COMMENTS
Interpretation of mixed-field reactions must be done with caution. The presence of fibrin, clots or particulates may
result in some cells layering at the top of the gel. Patient clinical information should be reviewed before concluding
a test is mixed-field. After the antibody identification has been done and if the identification is negative or
inconclusive, a prewarm screen may be done to help rule out a cold antibody.
LIMITATIONS
• Antibodies specific for low-incidence factors not represented on the test cells will not be detected.
• False-positive results may occur if antibodies to components of the preservative solution are present in the
serum tested.
• Significant variations in red blood cell suspensions may result in false-positive or false-negative reactions.
• Anomalous results may be caused by fresh serum, fibrin or particulate matter in serum or plasma, or red cells
that stick to the sides of the microtube. Anomalous results with fresh serum (i.e., a line of red cells on top of
the gel) May be minimized by the use of EDTA plasma.
• Adherence to the test procedure is critical to test performance.
REFERENCES
• AABB Technical Manual. 14th Edition, 2002; pp. 266-267.
• Technical Manual. 11th ed. Bethesda, MD: American Association of Blood Banks, 1993:309-30.
• Package Insert: Reagent Red Blood Cells SURGISCREEN. Raritan, NJ: Ortho Diagnostic Systems, Inc.
• Package Insert: Anti-Human Globulin Anti-IgG (Rabbit) MTS Anti-IgG Card. Pompano Beach, FL: Micro
Typing Systems, Inc.
• Package Insert: MTS Diluent 2 Red Blood Cell Diluent. Pompano Beach, FL: Micro Typing Systems, Inc.
• Malyska H, Weiland D. The Gel Test. Laboratory Medicine 1994; 25: 81-85.
The CHEO courses are evaluated using internal Hybrid or Online Course Review Tools based on criteria from project colleges'
Quality Assurance Standards developed by faculty and instructional designers. Periodic course review is ongoing.
Consortium for Healthcare Education Online project material by CHEO Project TAACCCT Round 2 is licensed under a
Creative Commons Attribution 4.0 International License“This product was funded by a grant awarded by the U.S. Department of Labor’s
Employment and Training Administration. The product was created by the grantee and does not necessarily reflect the official position of the
U.S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with
respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its
completeness, timeliness, usefulness, adequacy, continued availability, or ownership.”
2