Part I) Advanced Antibody Identification: Case Studies

95 Pages·2017·4.1 MB·English

by  Takara Blamires

Advanced Antibody Identification:
Case Studies
Justin R. Rhees, M.S., MLS(ASCP)CM, SBBCM
University of Utah Department of Pathology
Acknowledgements
• Thank you to the following scientists at the ARUP Immunohematology
Reference Lab (IRL) for contributing to several of the case studies used in
this presentation:
– Rebecca Whitney
– Catherine Thom
– Noel Pusey
– Becky Condas
1. Sally Rudmann, Ed. Serologic Problem-Solving: A Systematic Approach for
Improved Practice. 2005. AABB Press.
2. Guerlain S, Smith PJ, Obradovic JH, et al. Interactive critiquing as a form
of decision support: An empirical evaluation. Hum Factors 1999;41:72-89
3. Kanter MH, Poole G, Garraty G. Misinterpretation and misapplication of p
values in antibody identification: the lack of value in a p value.
Transfusion. 1997;37:816-822.
About me…
• B.S. Degree Medical Laboratory
Science/German
– Weber State University
• M.S. Degree Laboratory Medicine
and Biomedical Science
– University of Utah
• University of Texas Medical Branch
at Galveston (UTMB)
– Specialist in Blood Bank Technology
Training
– Board Certification American Society for
Clinical Pathology SBB(ASCP)
• Assistant Professor, Program
Director
– Medical Laboratory Science Program,
University of Utah
Nelda the Chicken
Objectives
1. Describe the principles and procedures of the
antibody identification tests.
2. Explain what factors make an antibody clinically
significant.
3. Given patient test results, correlate knowledge of
the serologic characteristics of several antibodies
and work through the procedures to correctly
resolve several antibody identification cases.
Principles and Procedures
of the tests
• “Why are there so many different procedures for
ABID?”
– The protocols that laboratories choose will affect what
they detect.
– Protocols should be tailored to the experience of the staff
and the general patient population encountered.
– Media needs to be taken into account
• Gel
• Solid Phase
• Tube
– Saline
– Albumin
– LISS
– PeG
– Enzymes
Clinical Significance
and Prevalence
An antibody is considered significant if it has been
associated with
– HDFN
– HTR
– Notable decreased survival of RBCs
– The degree of clinical significance varies among antibodies
with the same specificity
• Most commonly identified alloantibodies:
– Anti-D
– Anti-E
– Anti-K
Antibody Reactivity
in Various Media
Albumin LISS PeG Gel Solid Phase
May enhance Some examples Newly forming Increased Increased
Rh and anti-P of anti-K do not IgM antibody detection of detection of
1
antibodies react well in may not react antibodies that antibodies that
during the 37ºC LISS are not are not
spin phase Some examples clinically clinically
of anti-Jka not significant significant
detected
Can enhance Can enhance
Can enhance clinically benign clinically benign
clinically benign autoantibodies autoantibodies
autoantibodies
Sources:
Sally Rudmann, Ed. Serologic Problem-Solving: A Systematic Approach for Improved Practice. 2005. AABB Press.
John D. Roback, Ed. AABB Technical Manual, 17thEdition.
Denise Harmening, Ed. Modern Blood Banking and Transfusion Practices, 6thEdition.
Principles and Procedures
of the tests
• Use of sensitive media
– can enhance reactivity of antibodies that lack clinical significance
• Benign autoantibodies
• Anti-Ch, Anti-Bga, etc.
• Context
– A large transfusing facility with sickle patients, oncology, active transplant
programs, and other multiply transfused patients
– A medium-sized community hospital with a busy Labor and Delivery unit
– A small clinic in a rural area that stocks blood for trauma and transport
scenarios
• Staffing
– Level of training and experience
– Ratio of experienced technologists to new hires
– Experienced new hires vs. new MLS graduates
Principles and Procedures
of the tests
• Microscopic evaluation of macroscopically negative test tube
reactions?
• Use of the autocontrol in antibody screening and panels?
• Two- or three- cell screens?
• Screen and panel—methods the same?
• Variations in ruling out
– Homozygous for C, c, E, e, Duffy, Kidd, MNSs
• How many strikes?
– Heterozygous ok?
• How many strikes?
• Variations in ruling in
– 2/2 rule? 3/3 rule?
• Etc.
Principles and Procedures
of the tests
• Gather relevant patient information
• Observe and evaluate results
– Phase of reactivity: immediate spin, 37C incubation, AHG
– Incompatible crossmatches?
• Strength
– Hemolysis?
• Pattern
– Most or all cells positive, autocontrol negative
– 1 or 2 cells positive, autocontrol negative
– Panreactivity
– Variability—an antibody showing dosage effect, multiple antibodies, or antigen showing variable
expression from one panel cell to another
– Weak, variable reactivity
• Physical Appearance