43 Selected Panels (cells)

Some patients develop multiple red cell antibodies. In such cases, it is often difficult to meet the 3+3 rule. Additional –extra cells from other (different) panels are often required for conclusive identification or exclusion. Select cells are part of the “Rule In “or “Rule Out “process of antibody identification. If multiple antibodies exist the cell will need to be positive for one and negative for the other antibodies, it is preferred if the cell is homozygous as possible.

A “select” panel –full second panel-may be set up if not all clinically significant antibodies are excluded using the initial panel.

For example, Anti-Jka has not been excluded using the initial panel and screening cells and Anti-Fya is the suspected “probable” (direct hit) antibody:

1. Using the antigram record from an alternative panel (not the original panel used) select a cell that is ‘negative” for the antigen of the suspected “probable” (direct hit) antibody; i.e. Fy (a-); AND that is Jk (a+b-) or “homozygous” for the Jka antigen.
2. Set the additional cells up following the same method in which the antibody identification was performed i.e. SIAT with LISS/ Gel etc.
3. If the cell is “non-reactive” (no agglutination or negative), anti-Jka is excluded. If the cell is “reactive” or positive (has agglutination) then the patient has an anti-Fya AND an anti-Jka.

When multiple antibodies are suspected, the cells that are used to confirm the presence of the antibodies (select cells) may be positive for only one of the corresponding antigens at a time.

Example: Anti-Jka and Anti-E were not excluded and anti-Fya is the suspected “probable” (direct hit) antibody. Use an antigram from an alternative panel and/or screening cells (not the originals), select a cell(s) that is “negative” for the antigen of the suspected “probable” (direct hit) antibody  Anti-Fya requires Fy(a-) negative cells; then find cells to test for the remaining antibodies.

• Anti-Jka select” Fya “negative, “E” negative; AND  Jk(a+b-) or “homozygous” for the Jka antigen as possible. Be sure to test as many cells as needed to reach the 3+3 Rule.
• Anti-E select Fya negative,), “Jka” negative; AND that is “E” positive and “e” (E+e-) negative or “homozygous” for the “E” antigen as possible. Be sure to test as many cells as needed to reach the 3+3 Rule

4. Using the same method as used for the original antibody identification , set up additional cells and record results.

If select cells are just being used to eliminate “possible” antibodies (as a continuance of the exclusion process); multiple antigens may be present on the same cell. The only consideration when using this method is if one of the expected negative cells is positive it is necessary to repeat testing using only single antigens on the cells.

If there ARE definitely multiple antibodies identified, the 3+ 3 rule must be satisfied; which requires three positives and negatives for each ab/ag reaction.

Example; the results indicate the presence of anti-D, anti-c, and anti-K. Three cells need to be positive for D and negative c and K. Three cells need to be positive for c antigen but not D and K. Three cells with the presence of K antigen but not D and c. Three negative reactions for D, c and K negative cells must also occur. If the Rule is not met, additional cells will need to be tested until the the 3+3 rule is met.

Conclusive antibody identification occurs when the plasma containing the antibody is reactive with at least three antigen positive cells and negative with at least three antigen negative cells (3+3 rule). The patients’ phenotype must also be negative for the corresponding antigen(s) if the auto is negative.