Modification of tumor cells by a low dose of Newcastle Disease Virus.

Abstract

The present study elucidates the mechanism whereby viral xenogenization of highly metastatic ESb lymphoid tumor cells increases tumor immunogenicity and syngeneic tumor-specific T cell responses in comparison to nonmodified tumor cells. It was found that the frequency of cytotoxic T lymphocytes specific for the Esb tumor-associated transplantation antigen (TATA) and the cytotoxic anti-tumor activity in bulk cultures of immune spleen cells were significantly increased (by factor 3 and 25, respectively) when using virus-modified tumor cells. An amplified response was observed both in vivo and in vitro which might explain the demonstrated effectiveness of this approach for postoperative immunotherapy of ESb metastases. For the stimulation of tumor-specific cytolytic T lymphocytes (CTL) the ESb tumor cells which are highly metastatic were infected with an avirulent strain of the paramyxovirus Newcastle Disease Virus (NDV). Infection of ESb cells with low amounts of NDV was sufficient to lead to an increase in cytolytic activity of tumor-specific CTL after sensitization in vivo and restimulation in vitro. In a sensitive limiting dilution mixed leukocyte-tumor cell microculture system the direct effect of viral modification on the frequency and specificity of CTL was investigated. The number of ESb-specific CTL per spleen could be raised from about 3300 (without modification) to 9100 by both in vivo and in vitro application of ESb-NDV. One application of ESb-NDV (in vivo or in vitro) increased the number of CTL to 4900 and 4600, respectively. In split-type experiments it could be shown at the clonal level that viral modification did not alter the specificity of ESb-specific CTL.(ABSTRACT TRUNCATED AT 250 WORDS)

Viral hemagglutinin augments peptide‐specific cytotoxic T cell responses

“…Ltk-, ESb or EL4 cells were infected with NDV by incubation of lo7 cells for 1 h at 37°C with indicated amounts of NDV, followed by three washes with PBS. The peptide-specific cytotoxicity was measured in a standard 4-h 51Cr-release assay [14] against Ltk-cells preincubated with or without peptide. Different E/T dilution curves were compared by linear regression analysis (correlation coefficients >0.95).…”

“…tained in RPMI (Gibco BRL) containing 10% FCS (Gibco BRL). A stock of the avirulent NDV strain Ulster was grown in the allantoic cavity of 10-day-old embryonated chick eggs and purified as described [14].…”

“…One LU corresponds to the number of effector cells which cause 30% lysis of the target cells (5 x 10". The estimation of a trend between different groups of regression curves was calculated as described earlier [14].…”

“…Antigen-specific CTL responses can be augmented by cytokines such as IL-7 [8], IFN-y [9] or IFN-dfi [ 10-1 I] or by coreceptors expressed on the APC, for instance ICAM-1 [12], B7 [13] or by infection with Newcastle Disease Virus (NDV) [14]. The latter was seen for the generation of tumor-specific CD8+ CTL as well as for tumor-immune CD4+ T h cells [15].…”

Transloading of tumor cells with foreign major histocompatibility complex class I peptide ligand: a novel general strategy for the generation of potent cancer vaccines.

“…We sought to use this mechanism for the generation of cancer vaccines by using synthetic, nonself, but MHC-matched, virus-derived peptides to bring about immunogenicity in whole tumor cells. Tumor cells displaying foreign peptides should be efficiently recognized by the immune system and thus initiate an immune response against tumor-specific antigen(s) (6). To test this concept, we chose the N-terminal influenza hemagglutinin peptide derivative LFEAIEGFI (7), a putative ligand of the MHC class I haplotype H2-Kd.…”