IL-12 activity on primary MM cells. (A) Angiogenic activity of supernatants from one representative CD138⁺ MM sample cultured in the presence or absence of hrIL-12. CAMs treated with sponges loaded with the conditioned medium from the untreated cells were surrounded by allantoic vessels developing radially toward the implant in a “spoked-wheel” pattern (left panel). When medium from the same MM sample cultured with hrIL-12 was tested, a significant reduction of the angiogenic response was evident (right panel) (original magnification ×50). (B) Results from human angiogenesis PCR array performed in one representative CD138⁺ MM sample cultured in the presence or absence of hrIL-12 are shown. (C) Purified CD138⁺ primary MM cells incubated with IL-12 for 48 hours significantly up-regulated expression of the IFN-γ protein. Results are median mean fluorescence intensity (MFI) values plus or minus SE.