Figure 4.

Identification and morphology of lung DC after the i.n. delivery of BCG.Frozen lung tissue sections were stained with anti-I-A^q(a) or anti-CD11c mAb(b).Positive cells in red were easily detected in the peribronchiolar area and at a lower extent in the lung tissue. Original magnification ×20. The tissue sections shown are representative of 10 individual sections. All the CD11c enriched leucocytes purified from the lung tissue after i.n. delivery of BCG presented large nuclei and abundant cytoplasm with small cytoplasmic projections, the typical morphology of lung DC(c). A few cells had very long cytoplasmic processes, as shown in this higher magnification(d). Lung DCs purified after i.n delivery of unlabelled BCG (e) or CFDA-labelled BCG (f) were analysed by fluorescence microscopy after cytospin and Diff-Quick staining. Labelled bacteria are strongly fluorescent as compared to non labelled bacteria.