Administration of the protein hormone insulin can result in adverse immunological reactions that complicate the mangement of diabetes mellitus. Both IgE-mediated allergic reactions and IgG-mediated resistance are well-documented. In addition, insulin antibodies are present in most patients and may have subtle effects on diabetes control by altering pharmacokinetics and by accelerating vascular disease. These problems have not been eliminated by therapy with human insulin preparations. Insulin immunity is also part of the autoimmune prodrome of untreated Type I diabetes. This laboratory is examining the cellular and humoral mechanisms that regulate the immune response to insulin in man. In contrast to animal models, studies of human T cells show that the immunogenic determinants are often not predicted from amino acid differences. This complex human immune response includes T lymphocytes and antibodies that are specific for autologous insulin. In the proposed work, several approaches will be used to dissect this complex immune response. Insulin specific T cell clones have been produced, and these clones recognize distinct epitopes on the molecule in association with Class II MHC antigens. Using this approach, genetic elements that restrict T cell responses to the principal antigenic determinants on human and animal insulin will be identified. In addition, these clones will be used to investigate the role of antigen catabolism in the activation of T cells reactive to autologous, human insulin. To dissect the antibody response in these same subjects, monoclonal antibodies that recognize idiotopes on human anti-insulin antibodies were produced. These shared idiotopes are found on circulating anti-insulin antibodies and on antibodies produced by insulin-specific B cell lines from a number of subjects. These reagents will be used to initiate molecular studies of the germline and somatic mechanisms that generate the diverse anti-insulin repertoire in man. These studies are designed to identify the principal mechanisms that regulate insulin immunity in both treated patients and in Type I diabetics prior to insulin therapy. This information will provide insight into the role of insulin immunity in the pathogenesis of Type I diabetes and may identify therapeutic alternatives for the management of adverse immunological reactions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK032329-04
Application #
3230754
Study Section
Immunological Sciences Study Section (IMS)
Project Start
1983-12-01
Project End
1991-11-30
Budget Start
1986-12-01
Budget End
1987-11-30
Support Year
4
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Baylor College of Medicine
Department
Type
Schools of Medicine
DUNS #
074615394
City
Houston
State
TX
Country
United States
Zip Code
77030
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Thomas, J W (1993) V region diversity in human anti-insulin antibodies. Preferential use of a VHIII gene subset. J Immunol 150:1375-82
Miller, G; Nepom, G T; Reich, M B et al. (1993) Autoreactive T cells from a type I diabetic recognize multiple class II products. Hum Immunol 36:219-26
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Thomas, J W (1992) Anti-insulin and regulatory anti-idiotypic antibodies use the same germ-line VHIX gene. Eur J Immunol 22:2445-8
Nell, L J; McCammon, J A; Subramaniam, S (1992) Anti-insulin antibody structure and conformation. I. Molecular modeling and mechanics of an insulin antibody. Biopolymers 32:11-21
Ewulonu, U K; Nell, L J; Thomas, J W (1990) VH and VL gene usage by murine IgG antibodies that bind autologous insulin. J Immunol 144:3091-8
Miller, G G; Hoy, J F; Thomas, J W (1989) Insulin B chain functions as an effective competitor of antigen presentation via peptide homologies present in the thymus. J Exp Med 169:2251-6
Nell, L J; Hulbert, C; Thomas, J W (1989) Human insulin autoantibody fine specificity and H and L chain use. J Immunol 142:3063-9
Miller, G G; Hoy, J F; Nell, L J et al. (1988) Antigen processing and the human T cell receptor repertoire for insulin. J Immunol 141:3293-8

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