Test Catalog

Test ID: CEE20    
CD20 Cell Expression Evaluation, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Detecting cell-surface antigens on malignant cells that are potential therapeutic antibody targets, specifically CD20


Determining the eligibility of patients for monoclonal antibody therapies


Monitoring response to the therapeutic antibody

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

A complete diagnostic B-cell, T-cell, or acute immunophenotyping panel is not performed. In some cases, a limited morphologic evaluation will be performed.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Monoclonal antibodies are critical tools for detecting cellular antigens in various hematologic diseases and are used to provide critical prognostic information (CD49d). Monoclonal antibodies are also used as therapeutic agents in a variety of hematologic diseases. For example:

-Anti-CD20 (Rituxan): B-cell malignant lymphomas and multiple myeloma

-Anti-CD52 (Campath-1H): B-cell chronic lymphocytic leukemia and T-cell disorders

This list will undoubtedly expand over time to include other antibodies.


It may be necessary to document expression of these markers by the malignant cells prior to initiating the respective monoclonal antibody therapy. Expression of these markers may also be required for follow-up to monitor the impact of treatment on residual normal counterparts (eg, CD20-positive lymphocytes in patients treated with anti-CD20).


The distribution of these cellular antigens is well established in normal, reactive, and in various malignant disorders. The laboratory has several years of experience with therapeutic antibody monitoring of Mayo Clinic patients as part of the routine B-cell, T-cell, or acute immunophenotyping panels.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Normal individuals have B lymphocytes, T lymphocytes, or myeloid cells that express the corresponding cell-surface antigens in question.

Interpretation Provides information to assist in interpretation of the test results

The immunophenotyping report will summarize the pattern of antigenic expression on malignant cells and, if appropriate, the normal cellular counterparts that correspond to the therapeutic monoclonal antibody target.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Davis AT: Monoclonal antibody-based therapy of lymphoid neoplasms: what's on the horizon? Semin Hematol. 2000;37(4 Suppl 7):34-42

2. Czuczman MS, Grillo-Lopez AJ, White CA, et al: Treatment of patients with low-grade B-cell lymphoma with the combination of chimeric anti-CD20 monoclonal antibody and CHOP chemotherapy. J Clin Oncol. 1999;17:268-276

3. Flynn JM, Byrd JC: Campath-1H monoclonal antibody therapy. Curr Opin Oncol. 2000;12:574-581

4. Kreitman RJ, Wilson WH, Bergeron K, et al: Efficacy of the anti-CD22 recombinant immunotoxin BL22 in chemotherapy-resistant hairy-cell leukemia. N Eng J Med. 2001;345:241-247

5. Shanafelt TD, Geyer SM, Bone ND, et al: CD49D expression is an independent predictor of overall survival in patients with CLL: a prognostic parameter with therapeutic potential. Br J Haematol. 2008;140:537-546