Characterization of a human surfactant protein A1 (SP-A1) gene-specific antibody; SP-A1 content variation among individuals of varying age and pulmonary health

Departments of 1 Cellular and Molecular Physiology, 2 Pediatrics, 3 Obstetrics and Gynecology, and 4 Health Evaluation Sciences, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania; and 5 Department of Pulmonary Critical Care Medicine, Cleveland Clinic Foundation, Cleveland, Ohio Submitted 29 June 2006 ; accepted in final form 22 December 2006 The human surfactant protein A (SP-A) locus consists of two functional genes (SP-A1, SP-A2) with gene-specific products exhibiting qualitative and quantitative differences. The aim here was twofold: 1 ) generate SP-A1 gene-specific antibody, and 2 ) use this to assess gene-specific SP-A content in the bronchoalveolar lavage fluid (BALF). An SP-A1-specific polyclonal antibody (hSP-A1_Ab 68-88 _Col) was raised in chicken, and its specificity was determined by immunoblot and ELISA using mammalian Chinese hamster ovary (CHO) cell-expressed SP-A1 and SP-A2 variants and by immunofluorescence with stably transfected CHO cell lines expressing SP-A1 or SP-A2 variants. SP-A1 content was evaluated according to age and lung status. A gradual decrease ( P < 0.05) in SP-A1/SP-A ratio was observed in healthy subjects (HS) with increased age, although no significant change was observed in total SP-A content among age groups. Total SP-A and SP-A1 content differed significantly between alveolar proteinosis (AP) patients and HS, with no significant difference observed in SP-A1/SP-A ratio between AP and HS. The cystic fibrosis (CF) ratio was significantly higher compared with AP, HS, and noncystic fibrosis (NCF), even though SP-A1 and total SP-A were decreased in CF compared with most of the other groups. The ratio was higher in culture-positive vs. culture-negative samples from CF and NCF ( P = 0.031). A trend of an increased ratio was observed in culture-positive CF (0.590 ± 0.10) compared with culture-positive NCF (0.368 ± 0.085). In summary, we developed and characterized an SP-A1 gene-specific antibody and used it to identify gene-specific SP-A content in BALFs as a function of age and lung health. alveolar proteinosis; bronchoalveolar lavage fluid; cystic fibrosis; peptide antibody; surfactant protein A Address for reprint requests and other correspondence: J. Floros, Dept. of Cellular and Molecular Physiology, H166, The Pennsylvania State Univ. College of Medicine, 500 Univ. Drive, Hershey, PA 17033 (e-mail: jfloros{at}psu.edu )