CLINICAL LAB SCIENEC

CHAPTER 17: IMMUNOHEMATOLOGY (BLOOD BANKING) 419
This chapter provides a few routine tests performed in the routine blood banks.
The cross match, as mentioned earlier, is a rather long and cumbersome set of
tests, so the entire cross match will not be presented here. Medical laboratory
students enrolled in immunohematology classes usually learn both theory and
practice, and have the opportunity to perform an actual cross match.
Safety and Accuracy in Immunohematology
It should now be obvious to the astute clinical laboratory student that there is a
relationship between immunology/serology and immunohematology. Both areas
work on the premise of antibodies against antigens and require meticulous care
in providing accurate and timely results. However, in most routine procedures
in blood banking, the basic test are to discover RBC antigens by use of specific
antibody solutions obtained from persons with antibodies against various blood
groups. Efforts in this department are to obtain a safe supply of blood, test it
for communicable diseases, and ensure the patient has no antibodies against
the blood of the donor, which would cause a potentially life-threatening reaction.
The most atypical antibodies or alloantibodies (those from a donor) often
require a specialist in blood banking to determine the offending antibody.
In the Lab
BASIC IMMUNOHEMATOLOGY PROCEDURES
MANUAL IMMUNOHEMATOLOGY PROCEDURE #1
Preparation of 2% to 5% Cell Suspensions
Principle
A number of tests require red blood cell (RBC) suspensions and are performed in
test tubes. Other tests, such as blood grouping for identifying the ABO group, can be
performed either in test tubes or on glass microscope slides.
Red blood cells contain some plasma, which is rich in proteins. Surface proteins
may interfere with tests that use antisera against the antigens on the surface of the
RBCs. Therefore, the RBCs must be “washed” with normal saline (a salt solution
approximately equal to the salt concentration of a person’s blood plasma) to enhance
reactions in blood bank procedures.
To “wash” RBCs, several drops of RBCs are placed in glass test tubes (12 × 75 mm
tubes are preferable). Normal saline from a squeeze bottle is injected into the tube
containing the cells. Using a piece of plastic Parafilm, the top of the tube is covered
and the tube is then inverted several times to mix the cells and saline. The tube is
centrifuged, and the saline is removed, leaving a “button” of RBCs in the bottom.
This process is repeated two or three times, according to most blood bank basic
Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.