Antigen presenting cell activity in the lung is largely attributable to dendritic cells. We postulated that an immature dendritic cell precursor might be present within the pulmonary parenchyma. Furthermore, we postulated that the immunostimulatory capacity of pulmonary dendritic cells is not static but changes over time in response to local interactions with cytokines; growth factors, and parenchyma! cells. To test these hypotheses, we have isolated two populations of low density, nonphagocytic lung cells from lung digests of Balb/c mice. These two populations differ in their la expression (la bright and la dim). Both populations were CD45 positive (85-94%) and had similar expression of B7.1 (41-46% positive cells). Significant differences existed in B7.2 expression; 81% of the la bright cells but only 50% of the la dim cells expressed B7.2. la dim and la bright cells had different responses to growth factors in long term culture (18 days). Freshly isolated la bright cells were potent immunostimulatory cells in an mixed leukocyte reaction (10,500 cpm). Freshly isolated la dim cells were poor immunostimulatory cells (351±155 cpm) but their immunostimulatory capacity increased markedly in culture with M-CSF (14,151±2157 cpm). We conclude that the la dim cell population may either represent an immature dendritic cell sub-population or, alternatively, a second growth factor resoonsive Domilation of antieen oresentinE cells.
|Original language||English (US)|
|State||Published - 1996|
ASJC Scopus subject areas
- Molecular Biology