Effect of anti-MIF on vascularization during initial outgrowth of 38C13 B cell lymphoma. C3H/HeN mice were administered an i.d. injection of 38C13 tumor cells and then treated within 1 hr and at 1-day intervals with anti-MIF mAb (A, C, E) or control IgG1 mAb (B, D, F). The data shown were obtained with 0.5 mg of anti-MIF Ab per injection, and no significant diminution in capillary density was noted with ≤0.25 mg per injection. After 7 days, the tumor specimens were fixed, sectioned, and stained with hematoxylin and eosin (A, B), IgG2a isotype control (C, D), or antimurine CD31 mAb (E, F). Binding was detected with an alkaline phosphatase-linked secondary antibody.