Fig. 4.
IL-7 has diverse effects on mature T cells in vitro and leads to enhanced peripheral expansion in vivo.
Female C57BL/6 splenocytes were enriched for T cells using a positive selection column as described in “Materials and methods.” T-cell–enriched splenocytes were incubated in 24-well plates precoated with anti-CD3 at a suboptimal concentration of 0.1 μg/mL with or without rhIL-7 at 10 ng/mL. At days 2, 5, and 7, wells were harvested. Viable cells were counted with trypan blue exclusion and analyzed with flow cytometry. (A) By day 5 of culture, there is increased bcl-2 fluorescence intensity in cells incubated with rhIL-7 and stimulated by suboptimal anti-CD3 (heavy solid line) when compared to suboptimal αCD3 alone (gray dotted line) or media (light solid line). Isotype control shown as dark dotted line. (B) T-cell–enriched splenocytes were prelabeled with CFSE according to the manufacturer's instructions. At day 5, there is decreased CFSE intensity in a subset of T cells from wells incubated with suboptimal anti-CD3 in combination with rhIL-7 (solid line) when compared to suboptimal anti-CD3 alone or media only (dotted lines) indicating increased proliferation. Analogous results were obtained with H3 incorporation and the difference was not seen at optimal anti-CD3 stimulation (data not shown). (C) Incubation with suboptimal anti-CD3 and rhIL-7 (▪) results in increased viable T-cell number per well by days 5 and 7 compared to controls with suboptimal anti-CD3 (●) or media alone (♦). (D) TXY/TCD, C57BL/6 Ly 5.2 mice were injected intravenously with an inocula of 10 × 106 LN cells from normal or hbcl-2 transgenic donors (both Ly 5.1). One group receiving nontransgenic LN cells was treated daily with rhIL-7 at a dose of 5 μg/d intraperitoneally for 28 days. By day 28, there was a significant increase in the number of Ly 5.1+ T cells in the rhIL-7–treated group (n = 7, P = .004) or the group receiving hbcl-2 transgenic inocula (n = 7, P = .007) compared to control animals (n = 7). Data were analyzed using an unpaired t test.