Biochemical and immunological investigations into cystic fibrosis

Abstract

In an attempt to produce a quantitative biochemical assay which would assist in the detection of individuals heterozygous and homozygous for the cystic fibrosis (CF) gene, two general approaches were adopted. In the first, attempts were made to produce an antiserum specific for the cystic fibrosis factor (CFF), a substance known to be present in the serum and secreted by fibroblasts of both CF patients and heterozygotes. Three types of material were used for immunisation schedules - serum from CF homozygotes, the IgG fraction of CF serum and partially purified medium from CF fibroblasts. Both normal and neonatally tolerised rabbits were used in these experiments. The antisera produced were tested by immunoprecipitation, immunofluorescent and radiolabelling techniques. Immunoprecipitation and immunofluorescence showed that, after absorption, the antisera produced from fibroblast medium had specificity for CF samples. Sadiolabelling experiments indicated that the absorbed antisera produced from serum and the IgG fraction of serum also gave specific reactions with CF samples. However, all the antisera produced were too weak, but if suitable methods for fractionation and concentration of the antisera or production of stronger antisera could be perfected, one or more of these methods may prove suitable for the development of quantitative assays for CFF. The second approach involved an investigation of a claim made by Hosli, Erickson and Vogt (1976), that alkaline phosphatase is induced in CF fibroblasts by the addition of Tamm-Horsfall urinary glycoprotein. Alkaline phosphatase, alpha-glucosidase and hexosaminidase activities were measured in a series of normal and CF fibroblast lines, both before and after incubation of the cells with Tamm-Horsfall protein. No significant induction of the enzyme activities could be found in CF or normal control cell lines. It was therefore concluded that this method does not constitute a realistic approach to the development of methods for the diagnosis of homozygous and heterozygous CF individuals.