IG REPERTOIRE OF COMBINATORIAL AUTOANTIBODIES IN PBC

Project: Research project

Project Details

Description

The generation and characterization of human monoclonal antibodies, in
contrast to murine systems, has been difficult and with few
exceptions, non-productive. In fact, current hypotheses of Ig gene
usage in human organ specific autoimmune diseases are either
extrapolated from murine lupus or based on analysis of rheumatoid
factors. My laboratory has been successful in generating
combinatorial autoantibodies derived from the lymph node of patients
with primary biliary cirrhosis (PBC). These Fab autoantibodies are
directed at PDC-E2, the major autoantigen of PBC. Moreover, the
nucleotide sequence of our combinatorial autoantibodies suggest that
these antibodies are clonally related and reflect a restricted
response to PDC-E2. Moreover, the V-H genes show considerable somatic
mutation in CDR and three of these antibodies utilize a V-H germline
gene that has not hitherto been published. PBC is one of the few
autoimmune diseases for which a) the autoantigen and dominant epitope
have been identified; b) the genes coding for these autoantigens have
been cloned and sequenced; and c) recombinant proteins and synthetic
peptides are available. In this First Award I will take advantage of
these strengths and address several key questions. For example, we
will obtain additional data on the Ig gene usage encoding
autoantibodies to PDC-E2 and BCKD-E2: more than 90% of patients with
PBC react with one or more of these autoantigens. We will also
determine, as our pilot data suggests, that these autoantibodies are
encoded by a restricted response, reflect uncommon gene usage, and
have undergone somatic mutation. Additionally, we will determine
similarities which exist between the coding sequences of
autoantibodies to PDC-E2 compared to BCKD-E2. Finally, we will take
advantage of our random peptide library (peptide on plasmid) and
determine the autoepitopes recognized by these autoantibodies. We
will compare such data to epitopes determined by overlapping
recombinant peptides. Such data is important because by confocal
microscopy we have demonstrated that our combinatorial autoantibodies
stain a unique protein located only on the luminal side of bile duct
epithelial cells in patients with PBC but not PSC. Further data on
epitope recognition and mapping may shed further light on this issue.
The answers to these issues will have significant implications not
only for PBC, but also for other organ specific autoimmune diseases
and will provide significant data on the utility of combinatorial
autoantibodies.
StatusFinished
Effective start/end date7/1/936/30/99

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

ASJC

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

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