• Rittenberg, Marvin (PI)

Project: Research project

Project Details


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.
Effective start/end date4/1/783/31/04


  • National Institutes of Health: $352,658.00
  • National Institutes of Health: $332,415.00
  • National Institutes of Health: $342,386.00


  • Medicine(all)
  • Immunology and Microbiology(all)


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