To the Editor:
We read with interest the report by Massood et al1 on the source of the anti-Kaposi’s sarcoma (KS) activity observed in human chorionic gonadotropin (hCG) commercial preparations.2 The authors reported that a naturally occurring urinary dimer of 32 kD, known as antineoplastic urinary protein (ANUP), had a strong anti-KS activity that was still distinct from the activity observed in hCG preparations. Their observation highlights the complexity of crude preparations as well as the hazards relative to their clinical use.
Commercial preparations of hCG available in Belgium are Pregnyl (Organon, Oss, The Netherlands) and Profasi (Serono, Aubonne, Switzerland). We investigated the effect of these preparations on KS-derived spindle cells, established as reported by us and others.3,4 These cells were obtained from 1 patient with sporadic KS, from 1 renal transplant recipient, and from 2 acquired immunodeficiency syndrome patients. They overexpress the Bcl-2 protein and constitutively produce a 92-kD type IV collagenase, which suggests that they have a malignant potential.4,5 They did not react for the CD34 endothelial cell marker, whose detection on cultured KS-derived cells remains controversial.3,4,6,7 The hCG preparations were also tested on the immortalized KS cell line KS Y-18 (kindly provided by Dr Y. Lunardi-Iskandar, Baltimore, MD). Unexpectedly, we observed that all the tested lots of Pregnyl (lots no. 96H06 96D01, 96H06 96D10, and 97C18 96K21) had a net promitotic activity on the KS-derived spindle cells, independently of their epidemiological setting. By contrast, these preparations did not affect the growth of the immortalized KS Y-1 cell line. Neither Profasi nor recombinant hCG (gift from Dr G. Hennen, Liège, Belgium) modified the cell growth of any of the studied cell type (Fig1).
To our knowledge, no data have yet been reported on ‘paradoxical’ stimulation of KS cell growth by commercial hCG preparations. These findings raise the problem of the heterogeneous composition of clinical-grade hCG preparations. Crude hCG preparations are obtained from human pregnancy urine. They are tested for transmitted infectious agents, such as human immunodeficiency virus or hepatitis B virus, and contain a variety of hCG-related molecules as well as a mixture of biological contaminant substances. Several variables, including collection of urine from women at different gestational ages and from various latitudes (involving different environmental and genetic background), different modes of urine conservation, extraction, and purification, may make that a commercial preparation of hCG totally differs from another preparation in terms of biological activities.9 The absence or the inactivation of the anti-KS activity in certain commercial preparations of hCG could conciliate the present data with the poor clinical response observed in some clinical trials,10 stressing the need for the characterization of the anti-KS hCG-associated factors (HAF)11 and the availability of monoclonal antibodies to detect them. Because certain clinical-grade hCG preparations could not only lack the ability to control KS, but also contain some contaminant KS growth factor(s), we suggest a cautious use of these preparations in clinical practice.