The precise molecular interactions that occur between antigen and antibody in the active site determine whether a particular B cell will be selected to participate in an immune response. The nature of these interactions is the focus of this study using as a model system, monoclonal antibodies with a characteristic fine specificity that distinguishes between nitrophenyl phosphocholine (NPPC) and phosphocholine (PC); only NPPC blocks the binding of such antibodies to PC-protein. We call such antibodies Group II to distinguish them from T15-related anti-PC antibodies that bind both NPPC and PC (called Group I). Many """"""""natural' antibodies in nonimmunized animals, including man, are poly- and autoreactive. The polyreactivity of these molecules suggests that they may not obey the same molecular rules of antigen recognition as conventional antigen-induced antibodies which are not polyreactive; however, this is conjectural since few structural data are available regarding such antibodies. We propose to compare the binding sites of monoclonal poly/autoreactive antibodies that have the Group II fine specificity to antigen-induced Group II antibodies that are not polyreactive. Preliminary evidence derived from pairs of polyreactive and monoreactive Group II antibodies that use the same VH-VL gene combinations with a high degree of amino acid homology (ave 92%) suggests that VH CDR3 is an important distinguishing feature. We propose to test this hypothesis. We propose to test related hypotheses regarding the contributions of various regions of VH and VL to binding in conventional Group II antibodies and to examine the possible impact of these regions on polyreactive Group II antibodies. We propose to use site directed mutagenesis and chain recombination in transfectants to assess the contribution of H and L chains, and in particular the VH CDR3 of polyreactive antibodies. Through collaboration with an NMR spectroscopist we propose to compare the interactions of various ligands with the antibody active sites of conventional and polyreactive Group II antibodies allowing characterization in the solution state. We shall use computer assisted interactive molecular modeling to compare active site interactions in both types of antibodies and to guide molecular replacements to be achieved through directed mutation. Lastly we shall test the relative abilities of VH and VL in this system to undergo somatic mutation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI014985-16
Application #
2060146
Study Section
Immunobiology Study Section (IMB)
Project Start
1978-04-01
Project End
1997-01-31
Budget Start
1994-02-01
Budget End
1995-01-31
Support Year
16
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Oregon Health and Science University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Whitcomb, Elizabeth A; Martin, Tammy M; Rittenberg, Marvin B (2003) Restoration of Ig secretion: mutation of germline-encoded residues in T15L chains leads to secretion of free light chains and assembled antibody complexes bearing secretion-impaired heavy chains. J Immunol 170:1903-9
Wiens, Gregory D; Brown, McKay; Rittenberg, Marvin B (2003) Repertoire shift in the humoral response to phosphocholine-keyhole limpet hemocyanin: VH somatic mutation in germinal center B cells impairs T15 Ig function. J Immunol 170:5095-102
Wiens, G D; O'Hare, T; Rittenberg, M B (2001) Recovering antibody secretion using a hapten ligand as a chemical chaperone. J Biol Chem 276:40933-9
Wiens, G D; Lekkerkerker, A; Veltman, I et al. (2001) Mutation of a single conserved residue in VH complementarity-determining region 2 results in a severe Ig secretion defect. J Immunol 167:2179-86
Murray, S E; Lallman, H R; Heard, A D et al. (2001) A genetic model of stress displays decreased lymphocytes and impaired antibody responses without altered susceptibility to Streptococcus pneumoniae. J Immunol 167:691-8
Brown, M; Schumacher, M A; Wiens, G D et al. (2000) The structural basis of repertoire shift in an immune response to phosphocholine. J Exp Med 191:2101-12
Brown, M; Wiens, G D; O'Hare, T et al. (1999) Replacements in the exposed loop of the T15 antibody VH CDR2 affect carrier recognition of PC-containing pathogens. Mol Immunol 36:205-11
O'Hare, T; Wiens, G D; Whitcomb, E A et al. (1999) Cutting edge: proteasome involvement in the degradation of unassembled Ig light chains. J Immunol 163:11-4
Wiens, G D; Roberts, V A; Whitcomb, E A et al. (1998) Harmful somatic mutations: lessons from the dark side. Immunol Rev 162:197-209
Martin, T M; Wiens, G D; Rittenberg, M B (1998) Inefficient assembly and intracellular accumulation of antibodies with mutations in V(H) CDR2. J Immunol 160:5963-70

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