Complement-binding anti-Jka not detectable by DiaMed gels.

BACKGROUND

An anti-Jka was not detectable by the DiaMed-ID Micro Typing System but was strongly reactive when tested using other indirect antiglobulin test (IAT) methods. However, it was detectable in the DiaMed-ID system when the recommended diluent ID-Diluent 2, was replaced by other low ionic Strength saline (LISS) solutions. This led us to believe that the problem lay with the ID-Diluent 2.

METHODS

The anti-Jka was investigated using various low ionic strength diluents in the IAT against both polyspecific and monospecific antiglobulin reagents. We tested the ID-Diluent 2 for its ability to inhibit complement activation, and bind calcium.

RESULTS

The anti-Jka was shown to be a 'complement-only' binding antibody that reacted in all IATs performed except when tested with ID-Diluent 2. The ID-Diluent was shown to prevent haemolysis of ABO lytic antibodies, and further testing shows that it binds calcium.

CONCLUSION

The use of a diluent which prevents haemolysis and binds calcium in an IAT system that contains anti-complement as well as anti-IgG must be questioned.