Summary of Antibody Detection Phases

Table 3-1 provides a summary of phases used to detect antibodies. The table is not all inclusive; it gives typical reaction phases for the antibodies that are listed.

Table 3-1. Antibody Detection Methods.

	Serum/Cell Ratio	Incub Time/Temp	Controls	Abs Detected	Advantages	Disadvantages
Saline	*	15-60 min 4°, 22°, 37°	auto	M,N,P₁,Le^a, Le^b,I,(S),(Lu^a)	best for IgM; simple	detects cold abs, does not usually detect IgG
LISS 37°C (addition method)	2 dr PS 2 dr LISS 1 dr 3% rbc	15 min 37°	auto	as above (if reactive at 37°C)	as above; very sensitive (LISS- IAT); rapid	as above; increase thermal range of cold abs
Albumin addition	4 dr PS 2 dr 22-30% alb 1 dr 3% rbc	15-60 min 37°C	auto	Rh, (cold IgM abs as above)	? enhances some Rh	poor sensitivity; enhances some cold abs
One-stage enzyme	2 dr PS 2 dr enz 1 dr 3% rbc	15 min 37°C	auto	Rh, P₁, Le^a, Le^b, I	simple; rapid	denatures MNS,Fy^a,Fy^b, ags; may enhance some cold abs; [overincubation can cause false negs]
Two-stage enzyme	2 dr PS 1 dr 3% enz-rbc	15 min 37°C	auto pos/neg	as above + Kidd (enz-IAT)	increase sensitivity	as above except [ ]; more QC
IAT (Sal, LISS, Alb)	*	15-60 min 37°C	auto pos/neg IgG sens rbc	Rh, Kell, Kidd, Duffy, Ss, Lu^b	best for most IgG abs	complex; more QC

*Minimum ratio is 2 dr PS + 1 dr 3% rbc; 4 dr PS + 1 dr 3% rbc is more sensitive; 6 dr PS + 1 dr 3% rbc is used in "high volume serum" methods. Cell suspensions range from 1% to 5%, with 1% being most sensitive. ( ) some examples may react.

Enrichment activity #2

Read this Medline abstract of a paper by Peter Issitt on the lack of significance of enzyme-only antibodies . Based on the information, answer the following questions. E-mail responses to Pat.

How many samples contained apparently clinically significant enzyme-only antibodies in testing 10,000 patients?
How many patients received incompatible red cells as a result?
How many patients experienced a delayed hemolytic transfusion reaction?
Briefly explain why the authors conclude that, for routine pretransfusion tests, enzymes cause more work than the benefits are worth.
E-mail responses to the following questions to the class mailing list.
In your lab or geographical area, for which purposes are protease-treated enzymes used?
Which proteases are used routinely?
Do you agree with Issitt et al. that using proteases for pretransfusion testing causes more work than they are worth? Briefly explain.
Send a comment to the class list in reply to another student's response to Question #5, #6, or #7.
Briefly describe the routine quality control done in your laboratory (or geographical area) when doing IATS for antibody screening. For example, are positive and negative controls set up in parallel with tests or only as part of daily QC? Which antibodies are used in positive controls?
Briefly describe the routine quality control done in your laboratory (or geographical area) when doing direct antiglobulin tests using both polyspecific and monospecfic antiglobulin sera.

Summary