Transplanted tissue is attacked by T lymphocytes and antibodies; both recognize foreign (allogenic) HLA major histocompatibility complex (MHC) antigens. In order to better understand the immunopathology of transplant rejection, our long-term goal is to study antigenic sites (epitopes) on the human HLA-B7 transplantation antigen.
Specific Aim 1 : T Lymphocyte Epitopes. Two competing hypotheses describe how T lymphocytes recognize HLA allogenic epitopes. In the """"""""MHC only"""""""" hypothesis, T lymphocytes recognize HLA antigens alone, regardless of bound peptide; in the """"""""self peptide"""""""" hypothesis, T lymphocytes recognize an array of cellular peptides that are bound to allogenic HLA molecules. To judge these hypotheses we will test a panel of anti-HLA-B7 T lymphocyte clones from four donors against a series of 31 HLA-B7 variants. Variants with mutations in HLA surface amino acid residues will test the """"""""MHC only"""""""" hypothesis, whereas variants with mutants in HLA peptide- binding groove amino acid residues will test the """"""""self peptide"""""""" hypothesis.
Specific Aim 2 : Antibody Epitopes. We will test whether HLA-B7 epitopes fit the paradigm of soluble protein antigens, in which antibody epitopes are large, depend on three-dimensional conformation, include both variable and invariant amino acid residues, and are rarely affected by mutations at distant sites. To judge this hypothesis we will study four monoclonal antibodies (mAbs) that bind to physically non-overlapping sites on HLA-B7. We will test 15-20 HLA-B7 variants for each of the epitopes under study; each variant will have a point mutation within 15 A of a site known to control antibody binding. The pattern of antibody binding to these variants will allow us to assess whether HLA epitopes, like the soluble protein paradigm, are large and conformational, include both variant and invariant amino acid residues, and are spatially discrete. Health Relatedness. In addition to transplant rejection, HLA molecules also regulate the immunopathology of autoimmune disease and cancer. Thus, if we are to understand transplant rejection, autoimmune disease, and cancer, we must resolve how T lymphocytes and antibodies recognize HLA transplantation antigens. Such an understanding may lead to more specific treatment of these conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29AI027879-03
Application #
3455122
Study Section
Immunobiology Study Section (IMB)
Project Start
1990-08-01
Project End
1995-05-31
Budget Start
1992-08-01
Budget End
1993-05-31
Support Year
3
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Lutz, C T; Smith, K D; Greazel, N S et al. (1994) Bw4-reactive and Bw6-reactive antibodies recognize multiple distinct HLA structures that partially overlap in the alpha-1 helix. J Immunol 153:4099-110
Smith, K D; Valenzuela, A; Vigna, J L et al. (1993) Unwanted mutations in PCR mutagenesis: avoiding the predictable. PCR Methods Appl 2:253-7
McCutcheon, J A; Smith, K D; Valenzuela, A et al. (1993) HLA-B*0702 antibody epitopes are affected indirectly by distant antigen residues. Hum Immunol 36:69-75
McCutcheon, J A; Lutz, C T (1992) Mutagenesis around residue 176 on HLA-B*0702 characterizes multiple distinct epitopes for anti-HLA antibodies. Hum Immunol 35:125-31