Figure 2. Synergy between non–Fc-binding anti-CD3 and hpIIp in treating NOD and RIP-LCMV mice after overt diabetes.

Mice were treated with either the anti-CD3 or peptide alone [suboptimal dose of anti-CD3 F(ab′)₂ i.v. or hpIIp i.n., both 40 μg/injection] or a combination of both (combination therapy [CT]). (A) In the H-2^d RIP-LCMV model (upper panel), the efficacy of the combination treatment reached 50% (n = 34) compared with 20% with anti-CD3 alone (n = 26) or 0% with hpIIp alone (n = 6). In the NOD model (lower panel), the efficacy reached 55% with the combination treatment (n = 31), compared with 37% with anti-CD3 alone (n = 54) or 22% with the hpIIp alone (n = 9). At week 9 after treatment, the statistical significance was evaluated between the anti-CD3 alone and the combination therapy groups (*P < 0.05). (B) Pancreatic islets were scored for the presence of mononuclear infiltration (upper left panel). The average percentage shown was determined from at least 8 mice per group. Shown are histological stainings of pancreata from RIP-LCMV-NP mice (lower panels). At week 5 after treatment with anti-CD3 alone or in conjunction with the proinsulin peptide (CT), pancreata from protected animals were harvested. Six-micrometer tissue sections were cut and collected for immunochemistry. Sections were costained for insulin and NP expression (lower left panel). Sections were probed for cellular infiltration by CD4⁺ and CD8⁺ T cells (lower right panel). Representative sections are shown in each panel. Original magnification, ×20.