Fig. 3.
Alexa 594 RTX and Alexa 488 mAb 3E7 colocalize on Raji and ARH-77 cells only if RTX is bound to the cells in the presence of a C source.
(A-C) Alexa 594 RTX and Alexa 488 mAb 3E7 colocalize on cells opsonized in NHS or in citrated plasma. Cross-linking and capping are evident. (D) After opsonization with RTX in citrated plasma, ARH-77 cells were washed and probed with either Alexa 488 mAb 3E7 or FITC mAb HB43. (E-F) Alexa 594 RTX binds to cells in a homogeneous pattern if mAb 3E7 is omitted (panel E) or if NHS is omitted (panel F), and no cross-linking is observed. (G) When cells are opsonized in citrated plasma with Alexa 488 mAb 3E7, washed, and Alexa 594 RTX added, the probes do not colocalize, but they do colocalize when the order of addition is reversed (panel D). Original magnification × 250.