Abstract: A monovalent monoclonal antibody is provided, the antibody including one light chain, one heavy chain, and one truncated heavy chain, wherein the truncated heavy chain lacks a variable domain and a CH1 domain and wherein the antibody specifically binds an epitope of Fc?RI?. Also provided are methods of desensitizing a subject to an allergen, methods of treating an allergy, and methods of preventing an allergic reaction in a subject having an allergy.

Abstract: Provided is an immunotoxin including (a) an anti-CD19 antibody lacking an Fc fragment, (b) a modified exotoxin A protein having both Domains II and III, but lacking Domain I, and (c) a peptide linker joining the C-terminal end of the antibody to the N-terminal end of the modified exotoxin A protein. The linker is substantially resistant to extracellular cleavage. The modified exotoxin A protein may be further modified to include a C-terminal KDEL sequence (SEQ ID NO: 6) that promotes transport of the protein to the endoplasmic reticulum of cells that have taken up the immunotoxin. Also provided is an anti-CD19 antibody having enhanced binding activity, antibody-dependent cellular cytotoxicity (ADCC) and methods for using the antibody to treat a disease state associated with B-lineage cells that express CD19. The antibody variable light and variable heavy chains have unique sequences in their J region relative to known anti-CD19 antibody sequences.

Abstract: An immunotoxin for use in, and a method for treating a subject having a cancer associated with malignant B-lineage cells or an autoimmune condition, are disclosed. The immunotoxin includes (a) an anti-CD19 antibody lacking an Fc fragment, (b) a modified exotoxin A protein having both Domains II and III, but lacking Domain I, and (c) a peptide linker joining the C-terminal end of the antibody to the N-terminal end of the modified exotoxin A protein. The linker is substantially resistant to extracellular cleavage. The modified exotoxin A protein may be further modified to include a C-terminal KDEL sequence (SEQ ID NO: 6) that promotes transport of the protein to the endoplasmic reticulum of cells that have taken up the immunotoxin.

Abstract: A method of enhancing the antibody-dependent cellular cytotoxicity (ADCC) of a human or humanized CD19 antibody is disclosed. The antibody is produced in the presence of a beta.(1,4)-N-acetylglucosaminyltransferase III (GnTIII) enzyme, under conditions effective to produce in the antibody, an Fc fragment characterized by Asn297-linked oligosaccharides containing (i) at least 60% N-acetylglucosamine bisecting oligosasccharides, and (ii) at least 10% non-fucosylated N-acetylglucosamine bisecting oligosaccharides. Also disclosed is an anti-CD19 antibody, a composition produced by the method, a treatment method for cancers associated with malignant B-lineage cells, such as chronic lymphocytic leukemia, Non-Hodgkin lymphoma, and acute lymphoblastic leukemia, and a treatment method for autoimmune disease.