A CD22 test is a specialized diagnostic assay used to detect the CD22 protein, a surface marker found primarily on normal and malignant B lymphocytes. Typically performed using flow cytometry or immunohistochemistry on blood, bone marrow, or tissue samples, this test plays a vital role in diagnosing and classifying B-cell malignancies, such as B-cell acute lymphoblastic leukemia (ALL) and certain non-Hodgkin lymphomas.
By identifying CD22 expression, healthcare providers can determine a patient's eligibility for targeted therapies—including antibody-drug conjugates and CAR-T cell treatments—helping to guide personalized cancer care and monitor treatment response.