Figure 5.

Thymic nurse cells in 125-d/PRN baboons ± 2A11 treatment. (a) PGP9.5 immunostaining of thymus from one representative 125-d/PRN × 21-d animal that was treated with 2A11. Scale bar in lower left hand corner = 50 μm. Thymic cortex is located in the region between the two arrows. (b) Quantification of PGP9.5⁺ cells per in² thymic cortex. Groups tested were: 125 GCs (n = 4); 125-d/PRN × 14-d animals, no intervention (n = 5); 125-d/PRN × 14 d + 2A11 (n = 4); 125-d/PRN × 14 d + MOPC (n = 5); 125-d/PRN × 21-d animals, no intervention (n = 4); 125-d/PRN × 21 d + 2A11 (n = 5); 140 GCs (n = 5); Term (n = 3). *p = 0.005 compared with corresponding 125-d/PRN group with no intervention. ^†p < 0.04 compared with MOPC-treated 125-d/PRN group. Compared with 125 d GC: 140-d GC: p < 0.001; Term: p < 0.0001. ¥p < 0.001 for 125-d/PRN × 14 d with or without MOPC compared with 140-d GCs. **p = 0.002 compared to 125-d/PRN × 21 d with no intervention. Compared with 140-d GC: 14-d/PRN: p = 0.08. (c–e) Immunofluorescence staining of a thymus section from a representative 125-d/PRN × 21 d + 2A11 animal to verify the identity of the PGP9.5-positive cells from a as thymic nurse cells. Scale bar in the lower left corner = 50 μm. (c) PGP9.5 using phycoerythrin (red). (d) HLA-DR using fluorescein isothiocyanate (green). (e) Merged images from c and d demonstrate colocalization of both PGP9.5 and HLA-DR in nearly 100% of the positive cortical thymocytes, which appear yellow. Infrequent foci of PGP9.5-positive staining that lacked HLA-DR positivity were morphologically identified as nerve fibers or intrinsic ganglia (data not shown). (f) Phase contrast image of the same field as shown in c–e demonstrates thymic cortex in the lower half of the photomicrograph, with the capsule indicated by yellow asterisks and the approximate location of the corticomedullary junction indicated by a broken red line, so that the thymic medulla is at the top of the photo. A Hassall's corpuscle is indicated by an arrow. M = medulla.