EFFECT OF MARIJUANA ON MACROPHAGE ANTIGEN PRESENTATION

  • Nicola, Saleem M. (PI)
  • Cabral, Guy A. (PI)
  • Cabral, Guy A. (PI)
  • Cabral, Guy A. (PI)
  • Cabral, Guy A. (PI)

Project: Research project

Project Details

Description

Marijuana is the most common street drug of abuse in the United States. A
major proportion of AIDS patients are frequent users of psychoactive drugs,
including marijuana. Delta-9-tetrahydrocannabinol (THC), the major
psychoactive component of marijuana, accounts for the majority of its
immunosuppressive properties. The drug also inhibits macromolecular
synthesis, suggesting a mechanism by which it effects immunosuppression.
Macrophage play a central role in anti-microbial activities, in antigen
presentation, and in regulation of lymphocyte function. It is possible
that use of marijuana may compromise the immune system resulting in a
higher susceptibility to development of disease symptoms after AIDS viral
infection. Such higher susceptibility could result due to failure of
macrophages to synthesize and/or express molecules, such as la antigens,
which play a critical role in immune responsiveness against infectious
agents since processed viral antigens are presented to helper T cells in
the context of the heterodimeric la molecules. Alternatively, drug-induced
membrane perturbations could affect the synthesis of la molecules and/or
their interaction with processed exogenous antigen within the cell. The
goal of this research is to define the effect of THC on the synthesis,
post-translational modification, and expression of the major
histocompatibility la Class II molecules of murine macrophages. The
(B6C3)F1 mouse will be employed for in vivo drug exposure and as a source
of peritoneal macrophages. The macrophage line P388D1 will be used for in
vitro experiments. Murine gamma interferon or ConA supernatants from
murine splenocyte cultures will be used for induction of la expression.
Radiolabel pulse and pulse-chase experiments of macrophages labeled with
[35S]-methionine, [14C]-amino acids, or [3H]-glucosamine, and subjected to
one-dimensional or two-dimensional isodalt polyacrylamide gel
electrophoresis in concert within radioautography, will be performed to
establish the effect of THC on the time and rate kinetics of la molecular
synthesis. Antibodies will be employed for immunoprecipitation, Western
immunoblotting, immunofluorescence, and immunoelectron microscopy to
identify la molecules in gel profiles and to establish drug effects on
their compartmentation and cell surface expression. Murine [125I]-IgG2
will be employed in binding studies, and in ultrastructural experiments, as
a probe to define the effect of THC on receptor-mediated endocytosis. The
functional consequences of THC-induced alteration in la expression will be
assessed. The ability of THC-exposed P388D, macrophages to present peptide
fragments 1-65 and 81-104 of pigeon cytochrome c to the murine normal T-
helper cell clones, DB14 and A.E7, will be evaluated using a T-cell
proliferative assay and measuring 3H-thymidine incorporation. To
distinguish between impairment of antigen presentation versus co-
stimulatory activity, peptide receptor occupation will be assessed by
measuring the hydrolysis of myo-[2-3H] inositol to radiolabeled inositol
phosphates. The effect of THC on the secretion of the co-stimulatory
signal interleukin-1, requisite for replication of T-helper cells in
addition to antigen receptor occupancy, will be established using C3H/HeJ
mouse thymocyte proliferation.
StatusFinished
Effective start/end date5/1/915/31/00

Funding

  • National Institutes of Health
  • NATIONAL INSTITUTE ON DRUG ABUSE
  • National Institutes of Health: $25,472.00
  • NATIONAL INSTITUTE ON DRUG ABUSE

ASJC

  • Neuropsychology and Physiological Psychology
  • Medicine(all)
  • Cell Biology
  • Immunology

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