Lymphocytic acid-hydrolases and response to mitogens in cystic fibrosis.

In the present study, we compared the levels of a series of 
cultured lymphocytic acid-hydrolase enzymes in cystic fibrosis homozygotes, heterozygotes and controls; 
compared the effects of three different mitogens on these levels; and 
studied the effect of CF vs control serum in the culture 
medium. Our observations provide an entirely new interpretation for the apparent 
changes occurring in lymphocytic enzymes during culture of lymphocytes with mitogens, 
and suggest that a serum factor is present in cystic fibrosis 
serum that mimics mitogens in this regard. Lymphocytic acid-hydrolases and total 
protein are present in higher concentrations in lymphocytes cultured for 48 
hours without mitogen when CF homozygous or heterozygous serum is present 
in the culture media. This appears to result from a CF 
serum factor that has mitogen-like activity and prevents loss of cell 
protein during culture. Responsiveness of the cellular proteins to mitogens is 
blunted when CF serum is present in the culture media, either 
because the cell proteins are already maximally stimulated by the CF 
serum factor, or the factor blocks or modifies the action of 
mitogens on lymphocyte protein content. This phenomenon is useful for detection 
of CF heterozygosity, and appears to reflect the genetic abnormality causing 
cystic fibrosis. 