My Opinion: Use of Enzyme Panels

This is an updated version of a previous post.

Working for many years in the Middle East/Gulf, I have encountered significant antibodies that can only be detected at enzyme phase.  This is especially true of Rh system antibodies, particularly anti-c in an R1R1 patient.  I have attached an example.

The reasons I strongly recommend this practice are:

  1. Weak Rh system antibodies (as above)
  2. Confirmation of enzyme-labile antibodies, especially if there may be combinations of enzyme-labile and enzyme-resistant antibodies (e.g. anti-Fya and anti-c).

It is also important to consider which enzyme to use:  bromelin, ficin, or papain usually and sometimes trypsin or chymotrypsin.  They do not always attack at the same site.

In addition to most common MNSs and Duffy system antibodies, many Kell antibodies (e.g. K or K1, Kpa) are labile with papain:  however, with ficin they may be partially labile, unaffected, or even enhanced.

Using enzymes is a double-edged sword since they may enhance cold antibodies and thus cause nonspecific reactions.  Thus, I know many of you may not routinely include them in your workups.

It is essential to follow the manufacturer’s recommendations for their use.  If you make your own enzyme-treated cells and prolong the incubation, you may get false positivity.  You should also be careful about using potentiators with enzyme-treated cells—normally I run them in saline.

Since anti-c may cause severe hemolysis and severe hemolytic disease of the newborn, I am especially vigilant in my R1R1 patients, particularly females of child-bearing age and all chronically transfused patients.  I prophylactically match R1R1 patients with R1R1 RBCs in these categories, regardless if either anti-E or anti-c are expressed.  I have seen many examples where the anti-c is only detected at enzyme phase.

It is my practice to always include an enzyme panel.  I would be very interested to know your practices?  When do you use enzymes?