B-cells play a paradoxical role in preclinical disease models. In autoimmune diseases like Systemic Lupus Erythematosus (SLE) and Multiple Sclerosis (EAE), they are the primary pathogenic drivers. In immuno-oncology, their presence in the Tumor Microenvironment (TME) can either enhance anti-tumor immunity or actively suppress it.

To definitively study the role of B-cells in vivo, researchers require a highly potent, reliable tool for systemic cellular ablation. Enter the gold standard for murine B-cell depletion: Anti-Mouse CD20, Clone 18B12.

What makes Clone 18B12 the Murine Analog to Rituximab?

CD20 is a cell surface marker expressed almost exclusively on mature B-cells, making it the perfect target for targeted depletion. In human medicine, this pathway is targeted by the blockbuster biologic Rituximab (Rituxan).

However, human clinical drugs do not reliably cross-react with murine targets. Clone 18B12 was developed as the preclinical murine analog to Rituximab. It binds specifically to mouse CD20, allowing researchers to accurately model B-cell targeted therapies in immunocompetent, syngeneic mouse models.

The Importance of the Mouse IgG2a Backbone (Mechanism of Action)

Unlike blocking or neutralizing antibodies, a depleting antibody must physically destroy its target cell. Clone 18B12 achieves this because it is manufactured with a Mouse IgG2a isotype backbone.

In the murine immune system, the IgG2a isotype is the most potent inducer of Antibody-Dependent Cellular Cytotoxicity (ADCC) and Complement-Dependent Cytotoxicity (CDC). When 18B12 binds to CD20 on a target B-cell, its IgG2a Fc-region acts as a flare, recruiting natural killer (NK) cells and macrophages to rapidly and thoroughly lyse the B-cell. This results in profound B-cell depletion in the blood, spleen, and lymph nodes within days of administration.

Primary Applications for 18B12 In Vivo

• Autoimmune Disease Models: 18B12 is heavily utilized as a positive control in murine models of SLE (NZB/W F1 mice), Rheumatoid Arthritis (CIA models), and Multiple Sclerosis (EAE), where halting auto-antibody production is the primary therapeutic goal.

• Immuno-Oncology & Solid Tumors: Researchers are increasingly using 18B12 to ablate B-cells prior to administering immune checkpoint inhibitors (like Anti-PD-1 or Anti-CTLA-4) to determine if tumor-infiltrating B-cells are acting in a suppressive or anti-tumor capacity.

• Transplantation & GVHD: Used in conditioning regimens to prevent B-cell mediated allograft rejection.

Why Bulk Sizing and Low Endotoxin Purity are Critical

In vivo depletion protocols are famously resource-intensive. Achieving complete systemic ablation often requires dosing regimens of 250 µg (or more) per mouse, administered every two to three weeks.

Furthermore, introducing even trace amounts of endotoxin during a depletion assay can inadvertently activate macrophages and skew the entire immunological baseline of the model.

At ichorbio, our Anti-Mouse CD20 (Clone 18B12) Antibody is strictly formulated for in vivo use. It is ultra-low endotoxin, preservative-free, and available in 5mg, 25mg, 50mg, and 100mg bulk sizes, ensuring you can secure a single, highly pure batch for your entire animal cohort.

ichorbio's Anti-Mouse CD20 (18B12) Antibody is in stock in the UK and USA now!

(Don't forget to pair your depletion cohort with our strictly matched In Vivo Grade Mouse IgG2a Isotype Control).