Title:  Gel Card Sensitivity:  The Detection of Anti-M Antibodies and Dosage  Demonstrating Red Blood Cells
Students:  Nicole Spendlove, Zane Williams
Team: 2
Faculty Mentor: William Zundel
Date: October 17, 2004   

Abstract:

Serum containing anti-M antibodies cross reacts with M antigen positive red blood cells, especially those cells exhibiting dosage. The tube method has been primarily used to detect the presence of M antibodies until recently.  New Gel Technology allows for testing standardization and increased sensitivity to antibody/antigen reactions.  Anecdotal evidence in laboratory settings suggests that gel technology is not adequate to detect the presence and reaction of anti-M antibodies especially if a dosage related reaction

occurs. Traditional tube method reactions are compared to gel technology reactions. In conjunction, new and old reagent red blood cells are tested to determine gel technology sensitivity to anti-M antibodies.  Five to six anti-M positive specimens are tested against new and old, heterozygous and homozygous reagent red cells simultaneously.  Approximately 60 tests are conducted within a timeframe of several hours.  Data is collected in a blind study and interpretation is made by basis of comparison between the tube method and gel technology, then the relevance of the age of the red blood cell reagent. The study will place limitations on gel technology or resolve any doubts associated with identifying and quantifying anti-M dosage related reactions in vitro.

Introduction:

This research project relates directly to Blood Banking and the homozygous expression of the M antigen on red blood cells.  Typically anti-M antibodies demonstrate dosage or an increased reaction in vitro to cells that inherited a double dose of an antigen from the appropriate gene.  Traditionally, a tube method has been used to identify antibodies such as anti-M within the blood.  The tube method, as the name implies, uses test tubes as the reaction vessel for macroscopic reactions that indicate either a positive or negative test.  The tube method is inherently flawed because after centrifugation lab technologists must gently shake each tube to correctly read the test and assign a quantitative value to positive reactions.  Fortunately, recent technological advances have introduced to blood banking a new, more reproducible means of finding and identifying blood group antibodies.  This new blood bank discovery is generally referred to as gel card technology. Each gel card has microtubules that contain predetermined amounts of reagent and diluent.  A specific amount of serum is placed in each microtubule and then centrifuged.  After centrifugation, the test can be easily read with no shaking thus eliminating human error due to technique. However, it has been observed that Ortho-Diagnostics™ Gel Cards, when used in place of the traditional tube method, dosage has not been demonstrated and cannot be used with confidence to correctly assess blood compatibilities or identify antibodies such as anti-M that may cause a transfusion reaction.  Ortho-Diagnostics has yet to recognize the possible inconsistencies within the gel card technology stating that the age of the reagent cells is cause for any discrepancy not the actual Gel Cards.  To date no official study has been conducted using gel card technology to assess anti-M antibody sensitivity to red blood cells demonstrating dosage.

Objective:

If the issue of dosage demonstration in gel cards can be resolved more labs may opt to use this technology, rather than the conventional tube method since gel technology allows for standardization of testing.  No shaking or re-suspensions of cell buttons are necessary to assess reaction strength; allowing technologists the ability to consistently reproduce the test, even if different technologists perform the same test. Other advantages of gel technology include a decreased specimen sample and the elimination of technique-dependant procedures that may diminish test sensitivities in conventional tube methods.

If there are consistent tests within our research that do not react according to dosage principles the research will show that the gel technology is not sufficient to correctly assess blood compatibilities where anti-M antibodies and M antigens are presumed present.  The research will specify gel technology as a means of assessing dosage reactions or place limits on the use of gel cards in certain situations not currently defined.

Methods

Step 1: Anti-M positive specimens will be tested both by the tube method and gel technology to determine the correlation of dosage affected reactions between the two methods.

Step 2:  Anti-M positive specimens will be tested against homozygous and heterozygous panel cells, both new cells and older cells will be used to determine if the age of the cells are a factor in dosage reactions when tested by gel technology.  Three lot numbers of new panels cells will be used to test against the results obtained from three older lot number panels.

Note: In both cases the amount of specimens depends on the accessibility of Anti-M positive serum.  Our goal is to test 5 patients with a least 6 Homozygous cells and 6 Heterozygous cells in a blind study so that the age of the cell is unknown until after data has been collected.

Materials:

Approximately 30 Ortho Gel Cards

Anti-M (IgG) reagent anti-sera

6 different lot numbers of Ortho reagent red cells

5-6 hospital donated patient serum samples with known anti-M (IgG).

Test Tubes

AHG (Anti-Human Globulin) Antibodies

 References:

1. Harmening, D:  Modern Blood Banking and Transfusion Practices, ed. 4,  F.A. Davis

            Company, Philadelphia, p. 164, 1999.

2. Vincent, Janet M.S. M.T. (ASCP) S.B.B.  University of Texas Medical Branch, 

            Personal Interview,  September, 2004. 

Reviewers:

Leesa Gabrielson

Judy Ball