Use

This test is useful for evaluating patients with a suspected CD19 deficiency (humoral immunodeficiency) and confirming the complete absence of B cells in suspected primary humoral immunodeficiencies using both CD19 and CD20 markers. It is also used for assessing therapeutic B-cell depletion quantitatively in various clinical contexts, including malignancies, autoimmune diseases like rheumatoid arthritis and systemic lupus erythematosus, and in treating or preventing acute humoral rejection in positive crossmatch renal transplant recipients.