Summary:
SUMMARY
The high-strength low-avidity antibodies (HTLA) are part of a group antibodies
to red blood cell antigens that have been described as being of high titer but
low avidity so that the term HTLA is now applied to them. HTLA antibodies are
often the cause of incompatibility during routine compatibility testing making
almost all units of donors unsuitable for transfusion.
The term HTLA refers to one of the characteristics common to the majority
of these antibodies, namely they react at high dilutions (high-titer) but give
weak reactions(low-avidity) in each dilution of the titration. They are all
IgG immunoglobulis. The antigens they define include Csa(Cost), Yka(York),
Kna, Knb,(Knops) McCa to McCf(McCoy), Sla, Slb(Swain Langley), JMH(John Milton
Ha-gen), Gya(Gregory), Hy(Holley), Cha(Chido), and Rga(Rodgers). According to
their serological characteristics are divided into two groups, the
non-neutralizable and the neutralizable ones.
These antibodies, by definition, usually react at high dilution, but give
weak pos-itive reactions at each dilution. Weak positive reactions are not due
solely to the nature and concentration of HTLA antibodies, but also reflect
the nature of the respective antigens. Identifying HTLA is often complicated
and associated with ambiguous and difficult to interpret serologic reactions.
HTLA antibodies are often found in patients who have also developed other red
blood cell alloantibodies, and/or RBC autoantibodies, making the identification
of the HTLA antibodies even more complicated.
A case report of a multitransfused patient who has developed HTLA antibody is
presented.
Conclusion: The HTLA antibodies usually are not clinically significant and
transfu-sions with antigen positive red blood cells in patients who have
developed HTLA antibodies in most cases is not associated with adverse events.
Keywords:
High titer, Low avidity, Not clinically significant, Neutralizable - non neutralizable, IGg intibodies
