Typical Reactivity Pattern of an "HTLA" Antibody - LabCE.com, Laboratory Continuing Education

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The page below is a sample from the LabCE course A Comprehensive Overview of "HTLA" and "HTLA-Like" Antibodies. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about A Comprehensive Overview of "HTLA" and "HTLA-Like" Antibodies (online CE course)

Typical Reactivity Pattern of an "HTLA" Antibody

Since "HTLA" antibodies can be formed against many different antigens, and it is not uncommon for a patient to form multiple "HTLA" antibodies, reactivity can vary widely from one case to another. It is also important to note that not every "HTLA" antibody will display all common characteristics, however, there are some key hints that the majority of cases will demonstrate.

The example panel provided will display those common characteristics associated with "HTLA".

The first important observation in the example antibody panel is the weakly positive reactions with no apparent specificity.
Next note that "HTLA" antibodies will normally not have a positive autologous control. This can be a clue to distinguish between an "HTLA" antibody and a weak cold autoantibody as the reactivity on the panel cells may be extremely similar.
The reactivity will be a bit inconsistent, demonstrating weak/microscopically positive to 1+ reactions. If there are additional stronger reactions, this could be a clue that you have another antibody demonstrating in addition to the "HTLA" antibody.
Since the majority of "HTLA" antibodies are to antigens with a higher prevalence or to multiple antigens, reactions on >50% of panel cells will usually be seen. If there is reactivity that resembles an "HTLA" antibody but reacts with <50% of panel cells, this is likely an antibody to a human leukocyte antigen (HLA) which will require different steps to troubleshoot.

	Rh-Hr							Kell						Duffy		Kidd		Lewis		MNSs				P₁	Lutheran		Xg
Cell Number	D	C	c	E	e	V	C^w	K	k	Kp^a	Kp^b	Js^a	Js^b	Fy^a	Fy^b	Jk^a	Jk^b	Le^a	Le^b	M	N	S	s	P₁	Lu^a	Lu^b	Xg^a	AHG
1	+	+	0	0	+	0	0	0	+	0	+	0	+	+	0	+	+	+	0	+	+	+	+	+	0	+	0	w+
2	+	+	0	0	+	0	+	+	+	0	+	0	+	+	+	0	+	0	+	0	+	+	+	+	0	+	0	0√
3	+	0	+	+	0	0	0	0	+	0	+	0	+	0	+	0	+	0	+	+	0	0	+	+	0	+	0	1+
4	+	0	+	0	+	+	0	0	+	0	+	0	+	0	0	+	0	0	+	+	+	+	0	+	0	+	0	0√
5	0	+	+	0	+	0	0	0	+	0	+	0	+	+	+	+	+	+	0	0	+	0	+	0	0	+	0	w+
6	0	+	0	+	+	0	0	+	+	0	+	0	+	0	+	+	0	0	+	+	+	+	+	0	0	+	0	0√
7	0	0	+	0	+	0	0	0	+	0	+	0	+	+	0	+	0	+	0	+	0	0	+	+	0	+	+	1+
8	0	0	+	0	+	0	0	0	+	0	+	0	+	+	+	0	+	0	+	+	+	+	+	0	0	+	0	1+
9	0	0	+	0	+	+	0	0	+	0	+	0	+	+	+	+	0	0	+	0	+	+	0	+	0	+	0	w+
10	+	0	+	0	+	0	0	+	+	0	+	0	+	0	+	0	+	0	+	0	+	+	0	+	0	+	+	1+
AC																												0√

Note that the √ next to negative reactions is to confirm the AHG phase was functional. This step is referred to as Check Cells or Coombs check cells.