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.