HUMAN ANTIBODIES TO CRYPTOCOCCUS NEOFORMANS

Project: Research project

Project Details

Description

Cryptococcus neoformans meningitis occurs in 5-13% of individuals with
aids in the United States. As an initial infection it is associated with
the worst prognosis of all AID-associated infections. This project seeks
to establish a potential role for antibodies in immunity to human
cryptococcosis by demonstrating that anti-cryptococcal polysaccharide
antibodies can be identified in individuals who have been expose to C.
Neoformans. Although the traditional view is that immunity to
cryptococcosis is cell mediated, numerous studies have demonstrated the
importance of antibody-mediated processes. The presence of anti-
cryptococcal antibodies in HIV positive individuals is difficult to
predict since B cell defects that impair responses to encapsulated
bacteria and polyclonal stimulation of B cells have both been noted in
HIV infection. The basis of serologic studies to be performed is an
antigen-based ELISA. Serotype reactivity of HIV positive and HIV
negative individuals will be determined on purified cryptococcal
polysaccharide-coated ELISA plates. Associations between HIV status and
anti-cryptococcal antibody titer, antibody isotype, IgG subclass, and
antibody specificity will be examined in adults and children. Murine
anti-cryptococcal monoclonal antibodies will be used in competition
experiments with human sera in order to determine whether human anti-
cryptococcal antibodies recognize the same epitopes as existing
protective murine antibodies. Affinity chromatography and isoelectric
focusing will be utilized to further characterize human anti-cryptococcal
antibody responses. Preliminary studies of human anti-cryptococcal
polysaccharide antibodies with a rabbit anti-idiotypic reagent that
recognizes a protective murine anti-cryptococcal monoclonal have
demonstrated a cross-reactive idiotype in human and murine anti-
cryptococcal polysaccharide antibody response. Human anti-idiotypic
reagents will be generated in addition to human monoclonals to further
prove the nature of the human anti-cryptococcal antibody response. Two
monoclonal antibodies have already been isolated by EBV transformation
of human peripheral lymphocytes. Nucleic acid sequences of the
monoclonal will be determined to elucidate the molecular genetic
structure of human anti-cryptococcal antibodies and to evaluate the
nature of variable region gene element utilization in their derivation.
Correlates between serologic parameters or antibody structure and the
development or prognosis of C. neoformans meningitis in HIV positive
individuals would represent a powerful rationale for the use of antibody
proposal may provide new, urgently needed reagents for the therapy of
cryptococcosis as will as new insights into human C. neoformans immunity.
StatusFinished
Effective start/end date12/1/9311/30/94

Funding

  • National Institute of Allergy and Infectious Diseases

ASJC

  • Drug Discovery
  • Microbiology (medical)
  • Infectious Diseases
  • Virology
  • Immunology

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