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Kaposi's sarcoma (KS) is a relatively low grade neoplasm, classically occurring in the skin of elderly men. A more virulent and invasive form of Kaposi's sarcoma has been described in patients with acquired immune deficiency syndrome (AIDS). The origin and identification of the tumor cells in these lesions is controversial. Here we have studied the behavior of cells derived from KS lesions in an in vitro assay which measures the ability of cells to invade through a reconstituted basement membrane. In agreement with previous work, KS cells obtained under selective culture conditions were invasive showing activity comparable to that of malignant tumor cells. Normal fibroblasts, smooth muscle cells, and endothelial cells did not demonstrate invasive behavior under the same experimental conditions. To characterize further the nature of the KS cells we tested the chemotactic response of cells from the most invasive line to a variety of growth factors and compared their response to those of fibroblasts, smooth muscle, and endothelial cells. These studies suggest that normal cells respond to a unique repertoire of chemotactic factors. The chemotactic response of the KS cells most closely resembled that of smooth muscle cells and was quite distinct from endothelial cells. These results indicate that the KS-derived cultures contain invasive cells with a smooth muscle cell- like phenotype.

Infectivity of human T-cell lymphotropic virus, Type III (HTLV-III) was inactivated by heat more rapidly if in liquid medium than if lyophilized and more rapidly at 60 degrees than 56 degrees C. When HTLV-III was added to factor VIII suspension, then lyophilized and heated at 60 degrees C for 2 hours or longer there was elimination of 1 X 10(6) in vitro infectious units (IVIU) of virus. Much of the viral inactivation appeared to result from lyophilization. The application of water-saturated chloroform to the lyophilized material containing virus also resulted in elimination of infectivity. HTLV-III was efficiently inactivated by formalin, beta-propiolactone, ethyl ether, detergent, and ultraviolet light plus psoralen. The results are reassuring regarding the potential safety of various biological products.

Because of concern about the safety of immune globulins prepared for injection, we studied the effects of ethanol fractionation of human plasma on human lymphotropic virus, type III, (HTLV-III) by spiking the products of various fractionation stops with HTLV-III. Tests of inactivation and removal indicated that the ratio of residual live virus in plasma fractions/live virus in starting plasma was about 1 × 10-15 for precipitate II from which immune globulin for injection is manufactured. The results are reassuring regarding the potential safety of immune globulin.

Eight immunosuppressed homosexual men with cytomegalovirus viremia--seven with serious bilateral retinitis, one with colitis in addition to retinitis, and one with pneumonitis only--were treated with a new acyclovir derivative, 9-(1,3-dihydroxy-2-propoxymethyl) guanine, which has excellent in-vitro activity against cytomegalovirus. All patients had virologic and clinical improvement, but substantial leukopenia developed in three patients. Both clinical relapses and viral relapses occurred frequently, usually within 30 days after cessation of treatment. 9-(1,3-Dihydroxy-2-propoxymethyl) guanine represents the first clinically and virologically effective agent for the treatment of cytomegalovirus disease, but more effective and less toxic therapeutic regimens for both acute and chronic use must be developed.