The present invention provides compositions for altering a B cell mediated pathology in a patient. The compositions may comprise at least one and/or two chimeric proteins. Each chimeric protein comprises at least a portion of either the VH or VL region of a immunoglobulin molecule from particular B cells from a patient having a B cell mediated pathology, and an immunoglobulin constant region. The genes encoding VH and/or VL regions and the genes encoding immunoglobulin constant regions are isolated and inserted in an expression vector. The chimeric proteins may be produced by introducing the expression vectors into insect cell lines. Proteins may be further purified and conjugated to a compound such as an immunogenic carrier.