CD19+ and CD20+ marker detection to evaluate Rituximab effect

This is an immunological blood test designed to evaluate the quantity of B lymphocytes (CD19+ and CD20+) in peripheral blood and to monitor the efficacy of Rituximab treatment. The test is performed using flow cytometry, which allows precise identification and counting of cells with specific surface markers.

Rituximab is a monoclonal antibody that targets B cells with the CD20 marker, thus this test helps objectively evaluate the treatment effect.

What does this test show?

During the test, the following is determined:

• CD19+ cells – the total number of B lymphocytes in the blood (used as the main marker for identifying B cells);
• CD20+ cells – B lymphocytes with the CD20 surface protein, which is the target of Rituximab.

Results are presented as a percentage and (depending on the laboratory's methodology) as an absolute number (x10⁹/L).

After Rituximab treatment, a significant reduction or complete disappearance of CD20+ (and often CD19+) B cells in peripheral blood is expected.

When is the test recommended?

The test is performed:

• before starting Rituximab treatment (to determine the baseline level);
• during and after treatment to evaluate B cell depletion;
• to monitor B cell recovery after treatment;
• in cases of autoimmune diseases, hematological or oncological diseases when Rituximab treatment is applied;
• to assess treatment efficacy or the need for repeated therapy.

How are the results evaluated?

A significant decrease in CD19+ and CD20+ B lymphocytes indicates an effective treatment effect.

Gradual recovery of B cells can be observed after some time following treatment and is evaluated when deciding on further therapy tactics.

Interpretation of results is always done considering the clinical situation, diagnosis, treatment plan, and other laboratory indicators. The final assessment is provided by a specialist doctor.