FIG. 4.

Expression of CD25 and CD69 on CD4⁺ lymphocytes from the PB and BAL fluid of a healthy PPD⁻ subject. Viable cells were labeled and analyzed as described for Fig. 3. The distribution of events in each quadrant is given as percent CD4⁺ lymphocytes. Quadrants located in the same position are used to analyze both histograms. A cluster of CD25^bright CD69^bright events in the right histogram is indicated by an arrowhead. This subset constituted 8.4% of the CD4⁺ lymphocytes in this BAL fluid specimen.