The most common mutation of the cystic fibrosis transmembrane conductance regulator gene, CFTR, associated with the clinical disorder cystic fibrosis (CF) is called "APhe5N," a triple-base deletion resulting in loss of phenylalanine at residue 508 of the predicted 1480-amino acid CFTR CFTR gene expression quantified by limited polymerase chain reaction amplification showed that in normal individuals, CFTR mRNA transcripts are expressed in nasal, tracheal, and bronchial epithelial cells at -1-2 copies per cell, more than 100-fold greater than in pharyngeal epithelium. Importantly, allele-specific hybridization studies demonstrated that the normal and APhe5" CFTR alleles are expressed in the respiratory epithelium in similar amounts.Cystic fibrosis (CF) is a fatal recessive disorder caused by mutations of the CF transmembrane conductance regulator gene, CFTR, whose postulated protein product is a 1480-amino acid membrane protein thought to modulate Clsecretion across the apical membrane of epithelial cells (1-4). The most common mutation of the CFTR gene is called "Afe 508 ," a triple-base deletion resulting in loss of the codon for phenylalanine at residue 508 of the predicted protein sequence found on ;'"70% ofchromosomes containing an abnormal CFTR gene (3, 4). All organs with exocrine glands are affected by abnormalities of the CFTR gene, but the major clinical manifestations are in the respiratory tract, with impacted mucus, chronic infection, and inflammation with subsequent derangements of airways and lung parenchyma (1). It is not known how mutations in the CFTR gene cause the respiratory abnormalities, but it is assumed to be directly related to abnormalities in expression of the CFTR gene in the respiratory epithelium. As an approach to this question, the present study is directed toward quantifying in vivo CFTR gene expression at the mRNA level in respiratory epithelium of normals and individuals with CF. METHODS

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SummaryThe T cell receptor. (TCR) junctional regions (N regions) of the common human Vy9 and V62 gene segments were sequenced from the blood and lung of normal individuals (195 transcripts) and a group of individuals with sarcoidosis (220 transcripts), a granulomatous disease in which increased numbers of Vy9+ -y/b+ T cells are often observed. In normal individuals, the vast majority (86%) ofblood Vy9 transcripts used the JyP gene segment. In contrast to this restriction ofJ region usage, there was a large diversity of the junctional region, with <20% of blood Vy9 junctional regions showing identical sequences for any one normal individual. For the blood V62 transcripts in normal individuals, there was restriction of J region usage, with 93% using J61. The junctional regions were even more diverse than for Vy9, with a unique sequence observed in each transcript examined. Compared with blood, sequences from the normal lung showed a small increase in identical junctional regions, particularly in.one individual where 46% of Vy9 transcripts examined were identical, suggesting a response of some y/6 T cells to antigens found in the lung in the normal state . In marked contrast to normals, some individuals with sarcoidosis had large numbers of Vy9 transcripts, as well as VS2 transcripts, sharing identical sequences . For Vy9 blood transcripts, two individuals showed 84 and 56% ofjunctional region sequences to be identical, respectively. Similarly, blood VS2 transcripts showed 43, 33, and 25% identical junctional region sequences in three individuals . In the sarcoid patient with the most striking over-representation of blood Vy9junctional sequences, lung Vy9 transcripts showed increased (67%) use of the same junctional region sequence as in blood. This limited diversity of TCR junctional regions among some individuals with sarcoidosis suggests a response from specific stimuli, possibly antigenic, and that y/6 T cells may play a specific role in granuloma formation in sarcoidosis, as has been suggested in other granulomatous diseases.