To investigate the effect of subcutaneous (s.c.) treatment with an anti-CD20 immunoglobulin G1 antibody on B-cell depletion under the conditions of lipopolysaccharide (LPS)-induced inflammatory changes in mice.

Ofatumumab is a fully human anti-CD20 monoclonal antibody with a low-dose monthly s.c. autoinjection tailored for the treatment of relapsing multiple sclerosis. Currently, two Phase 3 trials on ofatumumab are ongoing and patient recruitment has been completed in both. We explored the effect of an anti-CD20 antibody (s.c.) on B-cell depletion and its impact on response to LPS using an LPS-induced inflammatory mouse model. The murine LPS model is a well-characterized preclinical model that involves the stimulation of a systemic toll-like receptor 4-driven inflammatory response in CD57/BL6 mice. This response mimics the key aspects of an infection-linked general inflammation.

C57/BL6 mice were subcutaneously treated with an anti-CD20 antibody or a control antibody 48 hours prior to the intraperitoneal administration of LPS at a low (0.5 mg/kg) or high dose (3 mg/kg). Mice were closely monitored for typical clinical signs. Blood samples were collected 24 hours after LPS administration and analyzed by fluorescence-activated cell sorting (FACS).

Treatment with a control antibody followed by LPS administration led to the typical clinical signs such as piloerection and hunched posture. Mice treated with the 3 mg/kg dose were more affected than those treated with the 0.5 mg/kg dose. However, treatment with an anti-CD20 antibody did not induce any deterioration of the state of the mice compared to the control treatment. FACS confirmed the depletion of B cells by the anti-CD20 treatment and revealed that LPS alone had already lowered the total cell count and lymphocyte count.

Treatment with an anti-CD20 antibody (s.c.) depleted B cells as expected without worsening the clinical signs of general inflammation induced by the effective doses of LPS.