Therefore, it acts by depleting normal as well as pathogenic B cells while sparing plasma cells and hematopoietic stem cells as they do not express the CD20 surface antigen.In the United States, rituximab is indicated to treat:

non-Hodgkin lymphoma (NHL)
chronic lymphocytic leukemia (CLL)
rheumatoid arthritis having inadequate response to one or more TNF inhibitors
vasculitis such as granulomatosis with polyangiitis and microscopic polyangiitis
moderate to severe pemphigus vulgaris
in combination with chemotherapy for children (≥6 months to <18 years) with previously untreated, advanced stage, CD20-positive diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma (BL), Burkitt-like lymphoma (BLL), or mature B-cell acute leukemia (B-AL). Blood cancers
Rituximab is used to treat cancers of the white blood system such as leukemias and lymphomas, including non-Hodgkins lymphoma, chronic lymphocytic leukemia, and nodular lymphocyte predominant Hodgkins lymphoma. This also includes Waldenströms macroglobulinemia, a type of NHL. Rituximab in combination with hyaluronidase human, sold under the brand names MabThera SC and Rituxan Hycela, is used to treat follicular lymphoma, diffuse large B-cell lymphoma, and chronic lymphocytic leukemia. It is used in combination with fludarabine and cyclophosphamide to treat previously untreated and previously treated CD20-positive chronic lymphocytic leukemia. Autoimmune diseases
Rituximab has been shown to be an effective rheumatoid arthritis treatment in three randomised controlled trials and is now licensed for use in refractory rheumatoid disease. In the United States, it has been FDA-approved for use in combination with methotrexate (MTX) for reducing signs and symptoms in adult patients with moderately to severely active rheumatoid arthritis (RA) who have had an inadequate response to one or more anti-TNF-alpha therapy.
Adverse events
Serious adverse events, which can cause death and disability, include:
Severe infusion reaction
Cardiac arrest
Cytokine release syndrome
Tumor lysis syndrome, causing acute kidney injury
Infections
Hepatitis B reactivation
Other viral infections
Progressive multifocal leukoencephalopathy (PML) caused by JC virus reactivation
Invasive fungal infections 
Immune toxicity, with depletion of B cells in 70% to 80% of lymphoma patients
Pulmonary toxicity
Bowel obstruction and perforationTwo patients with systemic lupus erythematosus died of progressive multifocal leukoencephalopathy (PML) after being treated with rituximab. PML is caused by activation of JC virus, a common virus in the brain which is usually latent. Reactivation of the JC virus usually results in death or severe brain damage.At least one patient with rheumatoid arthritis developed PML after treatment with rituximab.Rituximab has been reported as a possible cofactor in a chronic hepatitis E infection in a person with lymphoma. Hepatitis E infection is normally an acute infection, suggesting the drug in combination with lymphoma may have weakened the bodys immune response to the virus.A major concern with continuous rituximab treatment is the difficulty to induce a proper vaccine response. This was brought into focus during the COVID-19 pandemic, where persons with multiple sclerosis and rituximab treatment had higher risk of severe COVID-19. In persons with rituximab treatment for multiple sclerosis, 9 of 10 patients with B cell counts of 40/µL or more developed protective levels of antibodies after vaccination with tozinameran. Mechanisms of action
The antibody binds to the cell surface protein CD20.