Fig. 5.

Loss of dendritic cells due to apoptosis in H5N1 infected macaques. (A) CD83 staining in lungs and tracheobronchial lymph nodes was scored according to the following scale: 0 = none apparent; 0.5 = few/rare scattered cells; 1 = small numbers of positive cells, often in clusters; 2 = moderate increase in numbers of positive cells; 3 = moderate increase in numbers of positive cells; 4 = marked increase in interstitiae and/or BALT of the lung or in the paracortical zone of lymph nodes. Note: The entire section (min 7 sections per animal) was examined for CD83⁺ cells, translating into at least 30–60 high power fields. Day 6 death in H5N1 group is illustrated as day 7 for simplicity. A 2-way ANOVA was performed and revealed that groups were significantly different from one another (P < 0.001) over the entire course of the study, although not on any specific day. (B) CD83, activated caspase-3, and resulting double-labeling (100×) of apoptotic mature dendritic cells in lung tissue of an H5N1 animal on day 4. In most cases, apoptotic cells (caspase-3+) were identified as dendritic cells, mainly through morphology, due to the poor expression of CD83 in apoptotic cells.