Experience and protocols using the MTS Gel System for 'special procedures' 

A Transfusion Service shift supervisor in Los Angeles would like to know if other laboratories that use the MTS Gel System have developed protocols for using the MTS Gel System to perform 'special procedures' such as titration of Bg and HTLA antibodies, to distinguish between 'regular' red cell alloantibodies (like anti-K, anti-E) and those that are considered to be or which behave like high-titer/low avidity antibodies. The inquiring technologist comments that he would expect the MTS Gel System to show different titration results to those that have been observed in his laboratory in the past, when they used a tube test method for their titration studies. He also queries if laboratories have experience using the MTS Gel System for other special procedures such as neutralizations, elutions, etc. which have been successfully adapted.

The following response was received.

ADDENDA Feb. 29, 2004

1. John Judd of the University of Michigan (attribution used with permission) reports that the Gel anti-IgG test is nothing more than a modification of a tube antiglobulin test. In his opinion, Gel can be used whenever an indirect antiglobulin test (IAT) is required. In John's experience, Gel technology is especially helpful when his laboratory needs to make objective comparisons, such as when working with chemically-modified or ficin-treated red cells, and when performing inhibition studies, etc. [see reference 1]. The Gel system can also be used for eluate testing, especially the hemoglobin-free eluates obtained by acid-elution. [see reference 2] John emphasizes that his staff validated each of the above applications of the Gel system when introducing them into his laboratory.] John also reports that as part of their routine antibody identification studies, they always run ficin-treated RBCs by Gel when dealing with Rh antibodies other than D, especially, for example, when a c-E- patient has anti-E by tube methods. It is not uncommon for them to find an anti-c component by ficin-gel that is not evident by ficin-tube or by gel vs. untreated RBCs. [see reference 3] As for titrations by Gel, John reports that they have found anti-D titers to be 2-3-fold higher by Gel than by tube. [see reference 4] However, given that there is seemingly less reliance now on antibody titers in the management of HDN than there once was, John's laboratory continues to do prenatal antibody titers by tube, and not by Gel.
   • REFERENCE 1. Judd WJ, Steiner EA, Knafl PC, Masters C. The gel test: use in the identification of unexpected antibodies to blood group antigens. Immunohematology 1998;14:59-62.
   • REFERENCE 2. Steiner EA, Casina TS, Mann NN, Judd WJ. Comparison of acid eluates tested in gel vs. tube. Transfusion 1998;38(S):37.
   • REFERENCE 3. Judd WJ, Dake LR. Enzyme tests using anti-IgG gels. Vox Sang 2002;83(Suppl 2):154.
   • REFERENCE 4. Steiner EA, Judd WJ, Combs MR, et al. Prenatal antibody titers by the gel test. Transfusion 2001;41(S):31

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