What is High Titer Low Avidity?

Answer 1

HTLA ANTIBODIES = High Titer Low AvidityA summary of these antibodies are as follows

• Not clinically significant, but serological reactions make them look like they are
• High Titer if the antibodies are titered. The titers are usually at least 1:64 and often will be over 1:1000
• Reactions are very weak and will break apart very readily due to the weak attraction between the antigens and antibodies (low avidity).

These antibodies basically have a high titer but a very weak reaction. Some institutions actually score the strength of the antigen reaction in points which will allow them to differentiate some of the differences seen in various reactions.

Score = strength of reaction given points or score

• 4+ = 12 points
• 3+ = 10 points
• 2+ = 8 points
• 1+ = 5 points
• neg = 0 points

Specific serologic characteristics of the HTLA antibodies are:

• IgG
• React best in Coombs after 37oC incubation
• W+ to 1+ reactions
• React with most cells (antibodies to high-frequency antigens)
• Not clinically significant since they are not known to cause hemolytic disease of the newborn or hemolytic transfusion reactions. Since they are antibodies to high-frequency antigens they may mask clinically significant antibodies that are also in the serum.