Antiproliferative activity of conditioned medium from lymphocytes of neuroblastoma (NB) patient and inhibition with NB serum Rajendra N. Damle a , Ranga Rao b , Padma Shastry a, * a National Center For Cell Science (NCCS), (Autonomous Institute of Department of Biotechnology), Ganeshkhind, Pune 411 007, India b Command Hospital, Armed Forces Medical College, Pune 411 001, India Received 13 March 1999; received in revised form 28 June 1999; accepted 1 July 1999 Abstract Neuroblastoma (NB) is a pediatric malignancy and results in high mortality rate. Cellular immunity has been shown to play an important role in killing tumors ‘in vitro’. Human lymphocytes were activated in vitro with phytohaemagglutinin (PHA) and the effect of supernatants collected at 24, 48, 72 and 96 h were tested on proliferation of human NB cell line-SK-N-MC and glioma cell line U87-MG. The SK-N-MC cells were observed to be more susceptible to the supernatants compared to U87-MG with higher inhibition of proliferation as evaluated by [ 3 H]thymidine incorporation (P , 0:05 for 24 and 72 h and P , 0:0005 for 48 and 96 h). Conditioned medium from lymphocytes of NB patient collected at 48 and 96 h after activation inhibited proliferation (P , 0:005) of SK-N-MC cells. The presence of serum from NB patient decreased the antiproliferative activity of supernatants from normal lymphocytes and NB patient’s autologous lymphocytes (P , 0:01). This preliminary data demon- strates the capability of the activation of lymphocytes from NB patient undergoing aggressive multiagent chemotherapy and controlling proliferation of tumor cells on one hand and the role of serum from NB patient in abrogating to a certain extent the effect of activated immune cells thereby protecting tumor cells, on the other hand. Both these aspects need to considered with equal importance to study mechanisms in designing strategies for immune therapies. q 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Neuroblastoma; Glioblastoma; Activated lymphocytes; Conditioned medium; Proliferation 1. Introduction Neuroblastoma (NB) is a pediatric malignancy that results in high mortality rate. NB originate from neural crest and present with a variety of clinical and biologic features that are associated with diverse natural histories [1]. Although the conventional treat- ments like high dose chemotherapy and whole body irradiation followed by bone marrow transplantation have extended the long term survival of patients with metastasis, the prognosis of the disease is still very poor [4]. Cellular immunity has been shown to play an important role in killing tumor cells in vitro. Different subpopulations of the immune system have been tested for effectiveness in killing tumors [14]. Lymphocytes from normal volunteers and NB patients activated in vitro with IL-2 show increased cytotoxicity against NB cells, [2,15]. Susceptibility of NB cells to natural killer cells has been reported [7]. Cancer Letters 147 (1999) 5–10 0304-3835/99/$ - see front matter q 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S0304-3835(99)00254-2 www.elsevier.com/locate/canlet * Corresponding author. Tel.: 191-020-567-0931/41/51/61; fax: 191-020-567-2259. E-mail address: padmashastry@hotmail.com (P. Shastry)