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Test Code LAB1268 B-Cell Phenotyping Profile for Immunodeficiency and Immune Competence Assessment, Blood

Additional Codes

Mayo Test ID
IABCS

 

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Screening for common variable immunodeficiency (CVID) and hyper-IgM syndromes

 

Assessing B-cell subset reconstitution after stem cell or bone marrow transplant

 

Assessing response to B-cell-depleting immunotherapy

 

Identifying defects in transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI) and B-cell-activating factor receptor (BAFF-R) in patients presenting with clinical symptoms and other laboratory features consistent with CVID

Testing Algorithm

If immune assessment B-cell subsets test is abnormal, then confirmation will be performed at an additional charge.

 

When multiple specimen types are required to perform a panel of tests, the laboratory will perform the tests for which the appropriate specimen type was received and the laboratory will cancel those for which the appropriate specimen was not received. Please be advised that this may change the degree of interpretation received with the report. If only the refrigerate EDTA sample is received, this test will be canceled and converted to RBCS / Relative B-Cell Subset Analysis Percentage which provides the relative B-cell subset values without quantitation.

Method Name

TBBS: Flow Cytometry

IABC: Fluorescent Flow Cytometry

Reporting Name

Immune Assessment B Cell Subsets, B

Specimen Type

Whole Blood EDTA


Advisory Information


 



Shipping Instructions


Specimens are required to be received in the laboratory weekdays and by 4 p.m. on Friday. Draw and package specimen as close to shipping time as possible.

 

It is recommended that specimens arrive within 24 hours of draw.

 

Specimens arriving on the weekend may be canceled.



Necessary Information


1. Date of draw is required.

2. Ordering physician's name and phone number are required.



Specimen Required


Two separate EDTA specimens are required: 1 refrigerated and 1 at ambient transport temperature.

 

For serial monitoring, we recommend that specimen draws be performed at the same time of day.

 

Specimen Type: Whole blood for TBBS / Quantitative Lymphocyte Subsets: T, B, and NK

Container/Tube: 4 mL Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions:

1. Send specimen in original tube. Do not aliquot.

2. Label specimen as blood for TBBS / Quantitative Lymphocyte Subsets: T, B, and NK.

Specimen Stability Information: Ambient <52 hours

 

Specimen Type: Whole blood for IABC / B-Cell Phenotyping Screen for Immunodeficiency and Immune Competence Assessment, Blood

Container/Tube: Lavender top (EDTA)

Specimen Volume:

≤14 years: 4 mL

>14 years: 10 mL

Collection Instructions:

1. Send specimen in original tube. Do not aliquot.

2. Label specimen as blood for IABC / B-Cell Phenotyping Screen for Immunodeficiency and Immune Competence Assessment, Blood.

Specimen Stability Information: Refrigerated <48 hours


Specimen Minimum Volume

TBBS: 1 mL
IABC
≤14 years: 3 mL
>14 years: 5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Varies 48 hours

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

NA

Other

Specimen in aliquot tube (not in original Vacutainer)

Reference Values

The appropriate age-related reference values will be provided on the report.

Interpretation

Quantitative Lymphocyte Subsets: T, B, and NK :

When the CD4 count falls below 500 cells/mcL, HIV-positive patients can be diagnosed with AIDS and can receive antiretroviral therapy.

 

When the CD4 count falls below 200 cells/mcL, prophylaxis against Pneumocystis jiroveci pneumonia is recommended.

 

Immune Assessment B Cell Subsets, Blood:

The assay provides quantitative information on the various B-cell subsets (percentage and absolute counts in cells/microliter). Each specimen is evaluated for B-cell subsets with respect to the total number of CD19+ B cells present in the peripheral blood mononuclear cell population, compared to the reference range. In order to verify that there are no CD19-related defects, CD20 is used as an additional pan-B-cell marker (expressed as percentage of CD45+ lymphocytes).

 

The B-cell panel assesses the following B-cell subsets:

-CD19+=B cells expressing CD19 as a percent of total lymphocytes

-CD19+ CD27+=total memory B cells

-CD19+ CD27+ IgD+ IgM+=marginal zone or nonswitched memory B cells

-CD19+ CD27+ IgD- IgM+=IgM-only memory B cells

-CD19+ CD27+ IgD- IgM-=class-switched memory B cells

-CD19+ IgM+=IgM B cells

-CD19+ CD38+ IgM+=transitional B cells

-CD19+ CD38+ IgM-=plasmablasts

-CD19+ CD21-=CD21 low ("immature") B cells

-CD19+ CD21+=mature B cells

-CD19+ CD20+=B cells co-expressing both CD19 and CD20 as a percent of total lymphocytes

 

For isotype class-switching and memory B-cell analyses, the data will be reported as being consistent or not consistent with a defect in memory and/or class switching. If a defect is present in any of these B-cell subpopulations, further correlation with clinical presentation and additional functional, immunological, and genetic laboratory studies will be suggested.

 

Since each of the 11 B-cell subsets listed above contributes to the diagnosis of common variable immunodeficiency (CVID) and hyper-IgM syndromes and provides further information on the likely specific genetic defect, all the B-cell subsets are carefully evaluated to determine if further testing is needed for confirmation, including functional assays and genotyping, which is then suggested as follow-up testing in the interpretive report as detailed below.

 

If abnormalities are found in the B-cell phenotyping panel, the specimen will be reflexed to the CVID confirmation panel for assessment of defects in surface expression of B-cell-activating factor receptor (BAFF-R) and transmembrane activator and calcium modulator and cyclophilin ligand (CAML) interactor (TACI) (2 genes/proteins associated with CVID). To conclusively determine if TACI mutations are present, the TACI mutation analysis test by gene sequencing can be ordered (TACIF / Transmembrane Activator and CAML Interactor [TACI] Gene, Full Gene Analysis).           

 

CVID Confirmation Flow Panel:

BAFF-R is normally expressed on over 95% of B cells, while TACI is expressed on a smaller subset of B cells and a proportion of activated T cells.

 

The lack of TACI or BAFF-R surface expression on the appropriate B-cell population is consistent with a CVID defect.

 

Results will be interpreted in the context of the B-cell phenotyping results and correlation to clinical presentation will be recommended.

Day(s) and Time(s) Performed

Monday through Friday

Specimens are required to be received in the laboratory on weekdays and by 4 p.m. on Friday. No weekend processing.

Analytic Time

3 days

Specimen Retention Time

PBMC's are stored for 7 days at -70° C

Test Classification

See Individual Test IDs

CPT Code Information

T- and B-Cell Quantitation by Flow Cytometry

86355-B cells, total count

86357-Natural killer (NK) cells, total count

86359-T cells, total count

86360-Absolute CD4/CD8 count with ratio

 

B-Cell Phenotyping Screen for Immunodeficiency and Immune Competence Assessment, Blood

88184-Flow cytometry, first marker

88185 x 7-Flow cytometry, each additional marker

 

Common Variable Immunodeficiency Confirmation Flow Panel

88184-Flow cytometry, first marker (if appropriate)

88185 x 2-Flow cytometry, each additional marker (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
IABCS Immune Assessment B Cell Subsets, B 90416-9

 

Result ID Test Result Name Result LOINC Value
30296 CD19+ % of total Lymphocytes 8117-4
3321 CD45 Total Lymph Count 27071-0
3316 % CD3 (T Cells) 8124-0
29094 CD20+ % of total Lymphocytes 8119-0
3322 CD3 (T Cells) 8122-4
30298 CD27+ % of CD19+ B cells 89358-6
3319 % CD4 (T Cells) 8123-2
30300 CD27+ IgM+ IgD+ % of CD19+ B cells 89352-9
3325 CD4 (T Cells) 24467-3
30302 CD27+ IgM- IgD- % of CD19+ B cells 89350-3
3320 % CD8 (T Cells) 8101-8
30304 CD27+ IgM+ IgD- % of CD19+ B cells 89348-7
3326 CD8 (T Cells) 14135-8
30306 IgM+ % of CD19+ B cells 89346-1
3318 % CD19 (B Cells) 8117-4
30308 CD38+ IgM- % of CD19+ B cells 89344-6
30310 CD38+ IgM+ % of CD19+ B cells 89341-2
3324 CD19 (B Cells) 8116-6
4054 % CD16+CD56 (NK cells) 8112-5
30312 CD21+ % of CD19+ B cells 89356-0
30314 CD21- % of CD19+ B cells 89355-2
4055 CD16+CD56 (NK cells) 20402-4
3327 4/8 Ratio 54218-3
30297 CD19+ 8116-6
29095 CD20+ 9558-8
6657 Comment 48767-8
30299 CD27+ 89353-7
30301 CD27+ IgM+ IgD+ 89351-1
30303 CD27+ IgM- IgD- 89349-5
30305 CD27+ IgM+ IgD- 89347-9
30307 IgM+ 89345-3
30309 CD38+ IgM- 89343-8
30311 CD38+ IgM+ 89357-8
30313 CD21+ 25164-5
30315 CD21- 89354-5
30316 Interpretation 69048-7

Profile Information

Test ID Reporting Name Available Separately Always Performed
TBBS QN Lymphocyte Subsets: T, B, and NK Yes Yes
IABC Immune Assessment B Cell Subsets, B No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
CVID CVID Confirmation Flow Panel Yes No