Date of Award

1977

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Basic and Clinical Immunology and Microbiology

College

College of Graduate Studies

Abstract

The results of our personal studies of alpha-l-protease inhibitor (APi, formerly termed alpha-l-antitrypsin), the major inhibitor of protease in extracellular fluids, are presented in this dissertation. In the first chapter, we describe techniques used for APi quantitation and determination of Pi phenotypes. After a brief review of the available techniques, we report several improvements on our original technique of Pi phenotyping using thin-layer isoelectric focusing. Particular attention is given to biochemical and immunological methods for verification of the results obtained by isoelectric focusing. Three complementary techniques are reported: protease probe, crossed immunoelectrophoresis, and print immunofixation. Analysis of the results from print immunofixation, using microdensitometry, is of special interest. In the second chapter, the alleles and phenotypes of the Pi system are described. We report a detailed study of the distribution of the Pi phenotypes in two different populations and compare our results with those previously reported in the literature, including more than 30,000 subjects. We also correlate serum APi levels with the various phenotypes. Our results demonstrate the existence of three new allele products Mc, Mb, and I2. In addition, we report that serum levels of API are slightly elevated in subjects with the Mb or Mc allele, whereas a marked reduction is associated with the expression of the I allele. An additional study concerning Pi phenotype determination in cord blood is presented, and the origin of the pattern of APi in newborns is discussed. The importance of APi as a genetic marker is emphasized. The third chapter deals with the structure and biological role of APi. After a summary of the current knowledge on APi structure, we report an original investigation concerning desialylation of APi. The results suggest that sialic acids do no account for the microheterogeneity and polymorphism of APi. A study of the binding of elastase and trypsin with APi shows that, in excess of APi, a stable complex is formed. In contrast, in excess of proteases the complex is dissociated, with release of altered APi and of the protease previously inactivated. In the fourth chapter, the clinical consequences of APi deficiency are examined. The role of APi deficiency in pulmonary and liver diseases is reviewed, and evidence for its predisposing role in noatopic asthma of infancy, hemochromatosis, juvenile chronic polyarthritis, and squamous cell carcinoma is presented.

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