Figure 2. Picostim/IL2 treatment, while expanding Vγ2Vδ2 T cells, could confer immune resistance to TB lesions in lungs after pulmonary Mtb infection.

Shown are digital photos of cut sections of lung lobes from 12 representatives of 27 macaques (9 for each group). Lungs and other organs were obtained in complete necropsy at day 65 after Mtb infection. Macaque ID numbers are shown in upper left corners, with the right caudal(RC) lobe (infection site) indicated in each photo. Extent and severity of the lesions could be adjudged based on the examples pointed by large arrows for caseation pneumonia or extensive coalescing granulomas and by small arrows for less coalescing or small granulomas. Yellow arrows indicate the enlarged hilar lymph nodes with caseation. Note that four Picostim/IL-2–treated macaques (ID 8022, 8014, 8013, 8006: first two animals shown in this figure and last two shown in Fig. S1 in Text S1) did not show any detectable gross TB lesions. Other five Picostim/IL-2–treated macaques displayed more focal, less coalescing or less caseating TB granulomas than control groups. (see Fig. S1 in Text S1). Vertical/horizontal bars at upper right corner of each photo represent the 1-cm scale derived from the fluorescence rulers of original photos. >50% of saline/BSA and 10% of IL-2–treated controls had extrathoracic TB dissemination, which was not seen in Picostim/IL-2-treated macaques. The efficacy evaluation was done sequentially in three separate trials each involving Picostim/IL-2 group and control groups of a total of 27 macaques.