Quick Review Cards for Medical Laboratory Science

Comparison of Tube, Gel, and Solid-Phase

Testing

Immunohematology Review 437

TUBE TESTING GEL TESTING SOLID-PHASE TESTING

Reaction container

Principle

Pos rxn

Neg rxn

Adaptable to

automation?

Advantages

Note: A cell button in tube testing is a solid agglutinate—4+ rxn. A cell button in solid phase is unagglutinated cells—neg rxn.

Microplate with RBC membranes bound to

surface of wells.

Abs in sample attach to RBC ags on surface

of wells. After incubation, unbound ab re-

moved by washing. Anti-IgG-labeled indi-

cator RBCs added. Attach to abs bound to

reagent RBC ags during centrifugation.

Indicator RBCs adhere diffusely to surface

of well.

No adherence of RBCs. Button of RBCs in

bottom of well.

Yes

Standardized. More sensitive than tube

testing. Rxn stable 2 days.

Glass test tubes

Abs attach to correspon-

ding ags on RBCs, form-

ing bridges between

cells. RBCs agglutinate.

Agglutinated RBCs or

hemolysis

No agglutinated RBCs or

hemolysis

No

Low cost

Plastic microtube containing dextran-

acrylamide gel.

Ag-ab rxn results in agglutinated RBCs.

Gel acts as sieve. Large agglutinates

can’t pass through, remain at top.

Small agglutinates pass into gel.

Unagglutinated cells go to bottom.

Agglutinated RBCs suspended in gel.

Position indicates strength of rxn.

Larger agglutinates at top.

Button of unagglutinated RBCs in

bottom of microtube.

Yes

Standardized. More sensitive than

tube testing. Rxn stable 2–3 days; can

be captured electronically. AHG tests

don’t require washing or control cells.