Reaction Phase

Look at the phase in which reactions are occuring and see if the results match the reaction patterns on your panel.

• Reactions occurring only at immediate spin phase could indicate a possible IgM antibody, cold agglutinin, or rouleaux.
• Reactions occurring in the AHG phase could indicate a possible IgG antibody.
• Reactions occurring in both reaction phases could indicate a combination of both IgM and IgG antibodies or a strong IgM antibody that carries through to AHG phase.

If a tube method is used, reactions are usually read at immediate spin and AHG phase. If a gel method is used, reaction readings are done only at AHG phase.

Pattern

Comparing the pattern of reactivity of the sample reactions with that of the panel cells will help to determine which antibody or antibodies are present. If the reactions match, or closely match, a specific panel cell, that could be the antibody.

The strength of the reaction does not correlate with the clinical significance of the antibody present. It does correlate to the amount of antibody that is available to react. If reactions are strong at immediate spin (IS) phase and get weaker at antihuman globulin (AHG) phase, it is possible that a strong IgM antibody is present that is carrying through to the AHG phase (e.g., 4+ at IS and 1+ at AHG).

The presence of multiple antibodies should be considered if reactions vary in strength or there are two separate reaction patterns in the IS and AHG phases.