An oyster gill ciliostatic factor material has been isolated from the saliva of patients with cystic fibrosis (CF) by utilizing its ability to bind to α-amylase. It was quantitatively assayed by its ability to reversibly inhibit rabbit muscle glycogen debranching enzyme. The specificity of this CF factor material was investigated by comparing activities from the saliva of CF homozygotes (patients) varying in age, sex, and the severity of the disease; CF obligate heterozygotes (carriers); normal control subjects who had no family history of CF; non-CF asthmatic and allergic bronchitis patients; non-CF immunologically deficient patients with chronic respiratory problems; non-CF juvenile diabetic patients; non-CF pancreatic insufficiency patients; non-CF patients with obstructive liver cirrhosis; and non-CF patients with ectodermal dysplasia. The results show that the CF factor material isolated from CF saliva is specific to subjects with cystic fibrosis and is not associated with similar non-CF chronic disease states, nor is it produced as a result of an organ pathology associated with CF. There was no correlation between the amount of factor present in an individual CF homozygote sample and the severity of the disease. In the case of both the CF homozygote and heterozygote samples, there was also no correlation in either age or sex and the amount of factor present. The degree of inhibition produced by CF homozygotes compared to CF heterozygotes is characteristic of the autosomal recessive mode of inheritance of CF. This finding appears to associate the isolated CF factor material with the affected CF gene and suggests that the factor material is related in some way to the genetic lesion in CF.SpeculationThese studies indicate that the salivary cystic fibrosis factor material isolated by the glycogen-complex method is in some way dependent on the cystic fibrosis gene and is not associated with similar non-cystic fibrosis chronic disease states or produced as a result of the pathologic alterations in those organs commonly affected in cystic fibrosis.