Rhinovirus infection of the lower airways is now a recognized disease,associated withbronchiolitis and asthma.The bronchial epithelial cells are the host cells when rhinovirus infection occurs inthe airway.It was hypothesized that a pro-fibrotic growth factor response may occur in these infected cells,leading to production of a key transforming growth factor,TGF-β-1.Bronchial epithelial cells were inocu-lated with human rhinovirus and compared at day 1,3 and 5 to control non-infected cells.Cell culturesupernatant fluid and cellular RNA were isolated.The amount of released TGF-β protein was measured byenzyme-linked immunosorbent assay (ELISA).Expression of TGF-β at the level of transcription was mea-sured by polymerase chain reaction (PCR) and gel electrophoresis.The results show that at all time pointsstudied,TGF-β production is greater in the infected cells,as demonstrated by ELISA (P<0.05) and by semi-quantitative PCR analysis.It was concluded that bronchial epithelial cells infected with common cold virusand rhinovirus,showed higher levels of TGF-β.The production of TGF-β may be indicative of a normalrepair mechanism to counter inflammation,or in the setting of persistent asthma,could potentially lead toincreased fibrosis and collagen deposition. Rhinovirus infection of the lower airways is now a recognized disease, associated with bronchiolitis and asthma. Bronchial epithelial cells are the host cells when rhinovirus infection occurs inthe airway. It was hypothesized that a pro-fibrotic growth factor response may occur in these infected cells, leading to production of a key transforming growth factor, TGF-beta-1. Bronchial epithelial cells were inocumented with human rhinovirus and compared at day 1,3 and 5 to control non-infected cells. Cell cultures of supernatant fluid and cellular RNA were isolated The amount of released TGF-β protein was measured by enzyme-linked immunosorbent assay (ELISA). Expression of TGF-β at the level of transcription was mea-sured by polymerase chain reaction (PCR) and gel electrophoresis.The results show that at all time points studied, TGF-β production is greater in the infected cells, as demonstrated by ELISA (P <0.05) and by semi-quantitative PCR analysis. It was concluded that bronchial epithelial cells infected cted with common cold virus and rhinovirus, showed higher levels of TGF-β. the production of TGF-β may be a normal mechanism of to counter inflammation, or in the setting of persistent asthma, could potentially lead to in- creased fibrosis and collagen deposition.