Hapten-induced primary and memory humoral responses are inhibited by the infusion of anti-CD20 monoclonal antibody (IDEC-C2B8, Rituximab)

Blocking the elicited humoral immune response has proven useful in treating individuals with autoimmune disorders or those who are at risk of developi ng antibodies which might be pathologic, e.g., transplant patients. Unfortu nately, humoral immunity has evaded efforts at ablation and those therapies aimed at ameliorating it have resulted in only partial success. In additio n, some of the current anti-humoral therapies not only target B-cells but a lso cross-react with other elements of immune response, making these therap ies nonspecific. Thus there is a need in the clinical arena for specific an ti-humoral therapies. Here we report the impact of infusion of a chimeric m onoclonal, an anti-CD20 IgG, on the primary humoral and memory response aga inst a simple hapten (DNP) in a nonhuman primate model. Anti-CD20 IgG inter fered with the elicited humoral response and with the memory response when administered prior to antigen exposure. Furthermore, we provide evidence th at anti-CD20 blocks the humoral response by eliminating those B-cells capab le of responding to the hapten, (C) 2001 Academic Press.