Figure 4.

Therapeutic effect of intravitreous injection of an immunotoxin targeting on surface CD22. Murine intraocular B-cell lymphoma was induced (20,000 tumor cells per injection per eye) and treated with either control vehicle [PBS (pH 7.3)] or immunotoxin HA22 at various dosages on day 12 posttumor injection as described in the text; eye tissues were collected on day 21 and processed for histopathology.A, histopathology of ocular tissue in mice treated with control vehicle [PBS (pH 7.3)]. There is widespread colonization and invasion of tumor cells (arrows) and massive retina damage.B, mice treated with HA22 at 200 ng/eye/injection. There was no tumor colonization and invasion into the retina tissue but only inflammatory cells, suggesting a clearing process of tumors by the immunotoxin. Note also that there is no visible retinal damage by therapy (bottom).C, two representative animals treated with higher dose of HA22 (2,000 ng/mL). Again, no tumor was observed after immunotoxin treatment.Top, representative of some of the mice that had substantial retinal damage after high-dose HA22 treatment;bottom, some of the mice that showed relative milder retinal damage. There was no therapeutic effect when a control immunotoxin, erb-38, was used (see Supplementary Fig. S2).