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concentrations control distribution and therefore, numbers of naïve versus effector CD4 and CD8 T
cells.(6) It is generally accepted that lower CD4 T cell counts are seen in the morning compared to the
evening(9) and during summer compared to winter.(10) These data therefore indicate that timing and
consistency in timing of blood collection is critical when serially monitoring patients for lymphocyte
subsets.
Useful For: Diagnosis of hyper-IgM syndromes, specifically X-linked hyper-IgM (HIGM1) and
autosomal recessive hyper-IgM type 3 (HIGM3) Evaluation of isotype class-switching defects
Interpretation: An interpretive report will be provided. The absence of CD40LG on activated T cells
is consistent with X-linked hyper-IgM syndrome (HIGM1). The presence of CD40LG on activated T cells
is not consistent with HIGM1. The presence of a positive and negative population for CD40LG is
consistent with HIGM1 carrier status (mosaic). Negative CD40-muIg staining is consistent with HIGM1.
Positive CD40-muIg staining is not consistent with HIGM1. Some patients (~20%) show absent
(negative) staining with the CD40-muIg antibody, while there is positive staining for surface CD40LG on
activated T cells. This dichotomy is due to the presence of specific mutations in the CD40LG gene that
permit normal surface expression of the protein but abrogate function. Therefore, measurement of the
receptor-ligand binding function using the chimeric CD40-muIg antibody improves the specificity of the
assay, enabling identification of CD40LG-deficient patients who would be missed otherwise. The absence
of CD40LG protein expression or CD40-muIg binding is considered confirmatory for HIGM1. Genetic
testing is not necessary to confirm the diagnosis, but may be performed to identify the specific mutation
involved. The absence of CD40 on B cells is consistent with autosomal recessive hyper-IgM type 3
(HIGM3). The presence of CD40 on B cells is not consistent with HIGM3. Reduced or absent
class-switched memory B cells (CD27+IgM-IgD-) is consistent with a defect in isotype class-switching.
Normal numbers of class-switched memory B cells indicates the lack of an isotype class-switching defect.
Reference Values:
B-Cell Subset Pediatric Reference Values (n=98)
Results Expressed as a Percentage of Total Lymphocytes Percentage Absolute Count (Cells/mcL)
CD19+ 4.3-23.2 92.0-792.0
CD19+ CD20+ 4.2-24.1 85.0-767.9
Results Expressed as a Percentage of CD19+ B Cells Percentage Absolute Count (Cells/mcL)
CD19+ CD27+ 4.6-49.1 9.4-136.0
CD19+ CD27+ IgM+ IgD+ 0.2-12.0 0.8-42.7
CD19+ CD27+ IgM- IgD- 1.9-30.4 5.2-74.2
CD19+ CD27+ IgM+ IgD- 0.3-13.1 0.8-37.8
CD19+ IgM+ 32.8-82.6 46.0-596.0
CD19+ CD38+ IgM- 2.9-51.8 8.2-275.1
CD19+ CD38+ IgM+ 7.6-48.6 14.2-229.6
CD19+ CD21+ 94.5-99.8 89.4-780.1
CD19+ CD21- 0.2-5.5 0.9-25.5
B-Cell Subset Adult Reference Values (n=96)
Results Expressed as a Percentage of Total Lymphocytes Percentage Absolute Count (Cells/mcL)
CD19+ 2.8-17.4 90.0-539.0
CD19+ CD20+ 3.2-16.8 95.0-580.8
Results Expressed as a Percentage of
CD19+ B Cells
Percentage Absolute Count (Cells/mcL)
CD19+ CD27+ 6.3-52.8 18.0-145.0
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 991