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.

Answer 2

High Titer Low Avidity (HTLA) refers to a profile of antibodies that are present in blood, often found in autoimmune diseases like systemic lupus erythematosus. These antibodies have high levels (titer) but low binding strength (avidity) to their target antigens, leading to a risk of false positive results in laboratory tests.