Functional Assessment of Viability of Epithelial Cells

Comparison of Viability and Mediator Release in Healthy Subjects and Asthmatics

¹ The Hospital Aiguelongue, Montpellier, France.

This paper shows that epithelial cells recovered by bronchial brushing can be studied morphologically and functionally in asthmatics and normal subjects. Epithelial cells from asthmatic patients are less viable and more activated than those of normal subjects, suggesting a role for the epithelium in bronchial asthma. Bronchial epithelial cells can be recognized by their morphologic appearance as many of them are ciliated. Thus, they can be characterized by classical microscopic studies using May-Grundwald Giemsa staining. Although, it may be more accurate to discriminate these cells by the presence of cytokeratin using a monoclonal antibody, the results of this study did not show any difference between both methods. No eosinophils were observed in this study as assessed by May-Grundwald Giemsa staining. The observation that there is a significant difference in the viability of epithelial cells recovered from asthmatic and normal subjects indicates that, even in mild asthma, there is damage to the cells lining the airways. This decreased viability may explain the shedding of epithelial cells often observed in biopsy specimens obtained from asthmatics.

The finding that cells from asthmatics spontaneously release significantly higher amounts of 15-HETE or fibronectin compared to those obtained from normal subjects suggests that these cells are in a state of activation. These findings may accord with the data showing that epithelial cells from asthmatics express more HLA class II antigens than those of normal subjects. Interestingly, there was no difference in the spontaneous release of PGE₂, although A23187 induced the release of this mediator from cells obtained from asthmatic donors, suggesting that cells from asthmatics may be "primed" for activation.

Thus, airways epithelial cells appear to be less viable and more hyperreactive in asthmatics as compared to healthy subjects, and they may also play a role in the presentation of antigen in asthma.