Psoralen/UV Inactivation of HIV-1-Infected Cells for Use in Cytologic and Immunologic Procedures

A rapid procedure for the inactivation of HIV-1-infected cells using psoralen and ultraviolet (UV) light is described. Exposure of HIV-1-infected cells to 5 μg/ml psoralen followed by UV irradiation (320-380 nm) for 5 minutes yields cells that are noninfectious as assessed by extended infectivity assays. The psoralen/UV inactivation procedure described is effective with cells chronically or acutely infected with HIV-1 and is unaffected by cell densities up to 12 × 10⁶/ml. At 5 μg/ml psoralen does little damage to cellular permeability as shown by the ability of treated cells to exclude trypan blue and propidium iodide. Psoralen/UV treatment of HIV-1-infected cells does not cause a significant decrease in the reactivity of HIV-1 core and envelope antigens or cellular antigens to monoclonal antibodies. Experiments are presented demonstrating the use of these cells for flow cytometry studies and for cell surface labeling using the lactoperoxidase ¹²⁵I iodination procedure.