Anna Bonmassar

Increased immunogenicity of L1210 leukemia following short-term exposure to 5(3,3′-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) in vivo or in vitro

SummaryShort-term exposure of L1210 Ha leukemia to DTIC in vivo or in vitro resulted in the generation of leukemic cells that were moderately immunogenic for histocompatible (BALB/C × DBA/2)F1 (CD2F1) mice. In vivo treatment was carried out in the peritoneal cavity of CD2F1 host for 8–36 h. In vitro experiments were performed in glass vessels, in which tumor cells were incubated with DTIC for 2 h at 37° C. The in vitro generation of immunogenic leukemia was conditioned by the presence of mouse liver microsomes capable of producing metabolic transformation of DTIC. It follows that the increase of tumor cell immunogenicity produced in vitro and possibly in vivo by DTIC is due to (a) metabolic product (s) that has (have) not yet been identified. Somatic mutation, selection, viral activation, or other mechanisms could be responsible for the DTIC effect. The present studies suggest that similar in vivo or in vitro techniques could be used to obtain human tumor cells with higher immunogenicity.

Appearance of strong transplantation antigens in non-immunogenic lymphoma following drug-treatment in vivo

A chemically induced lymphosarcoma line (LSBM-1) of C57BL/10 (H-2b) origin lacks detectable TATA and is scarcely immunogenic for H-2-incompatible congenic recipients. New antigenic specificities, defined as drug-mediated tumor antigen(s) (DMTA) were found in a subline (LBD-1) obtained by in vivo treatment of LSBM-1 with the anti-neoplastic agent dimethyl-1-triazeno-imidazole-carboxamide (DTIC) over several transplant generations. It was concluded that the presence of detectable TATA is not a prerequisite for the induction of new antigenic specificities (DMTA).

Changes of the immunogenic properties of K36 lymphoma treated in vivo with 5(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (DTIC)☆

Abstract Mice of AKR strain bearing syngeneic K 36 lymphoma were treated with DTIC for a number of transplant generations. The lymphoma line (K36/DTIC) became resistant to DTIC treatment and weakly immunogenic for AKR or (AKR × DBA/2)F 1 hosts. Previous findings, however, showed that DTIC-treated H-2 b or H-2 b lymphomas became DTIC-resistant as well, but acquired strong immunogenicity for histocompatible hosts. Transplantation resistance of allogeneic mice against K 36 or K36/DTIC lines injected i.p. or i.v. was also investigated. Both lines inoculated i.p. were rejected by either H- 2 -incompatible recipients, or H- 2 -compatible mice incompatible for minor histocompatibility loci (MIH). When the tumors were injected intravenously, H- 2 -compatible MIH-incompatible mice were more susceptible than H- 2 -MIH-incompatible recipients to lymphoma challenge. Moreover K36/DTIC line elicited stronger transplantation resistance than K 36 tumor. Unexpectedly H- 2 -MIH-incompatible mice homozygous for the H-2 d haplotype were partially susceptible to the i.v. challenge with K 36 lymphoma cells. However, strong transplantation resistance was found in the same hosts against K36/DTIC line. In conclusion the limited increase of tumor cell immunogenicity obtained by treatment of K 36 lymphoma with DTIC was detectable in syngeneic, hybrid and allogeneic mice.

Expression of normal histocompatibility antigens in murine lymphomas treated with 5-(3,3′-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) in vivo

Abstract Novel transplantation antigens have been detected in a Moloney virus-induced LSTRA lymphoma of BALB/c origin ( H-2 d ), or in a chemically-induced L5178Y lymphoma of DBA/2 origin, following treatment of tumor-bearing hosts with 5-(3,3 ′-dimethyl- 1 -triazeno-)-imidazole- 4 -carboxamide (DTIC), for 4–8 transplant generations. Marked cell-mediated cytotoxic responses against DTIC-treated LSTRA or L5178Y lines were found by primary in vivo and secondary in vitro sensitization of histocompatible mice. Moreover, preliminary data show that no obvious antigenic cross-reactivity can be found among DTIC-treated sublines derived from distinct parental lymphomas. To test whether DTIC lines would express variable levels of normal histocompatibility antigens, cytotoxic lymphocytes were generated in vitro against alloantigens of H-2 complex or sub-regions of it and tested against parental or DTIC-treated lymphomas in a short-term 51 Cr -release assay. A cold-inhibition test was performed with LSTRA or 4 LSTRA/DTIC sublines. The results showed that little or no difference in the expression of H-2 antigens recognized by cytotoxic lymphocytes could be detected between parental and DTIC-treated sublines. Moreover, no foreign H-2 specificities of H-2 b or H- 2 k haplotypes detectable by cytotoxic lymphocytes could have been found in L5178Y or L5178Y /DTIC lymphomas.

Immunologic response of mice bearing leukemia l1210.

The primary antibody response of mice bearing transplanted leukemias was studied using the direct plaque‐forming cell (PFC) technique. Decrease of the immune response was found in mice bearing advanced isogenic or allogeneic leukemia, whereas normal or even increased PFC response was seen when the antigenic stimulus was given at an early stage of the disease. Leukemia remission induced by 1,3‐bis(2‐chloroethyl)‐1‐nitrosourea (BCNU) did not prevent the immunosuppression of leukemic mice, although the same treatment schedule did not interfere with antibody production in nonleukemic animals.

Soluble factors produced by normal or tumor cells, inhibiting the uptake of 5-iodo-2'-deoxy-uridine by cancer cells in vitro.

Abstract The uptake of 125 I- 5 -iodo-2′-deoxy-uridine ( 125 IUdR) by lymphoma cells is inhibited in lethally irradiated hosts incompatible for Hh (hemopoietic-histocompatibility) loci. In the course of attempts to reproduce this phenomenon in vitro , a soluble factor (uptake inhibiting factor, or UIF) was found in the supernatant of cultured ( 16 hr, 37°C ) spleen cells. UIF was produced by non-stimulated splenocytes of various strains of conventional and athymic (nude) mice and rats and by various tumor lines as well. UIF was found to be non-strain, non-species and non-tissue specific, since it was capable of inhibiting the 125 IUdR uptake of mouse, hamster and human tumor cells of various tissue origins. Lethal irradiation, silica or IDF (immunodepressive factor) treatment of donor mice, or irradiation or treatment with actinomycin D of spleen cells in vitro , did not prevent UIF production by such cells. On the other hand 5 -fluoro- 2 ′-deoxy-uridine (FUdR) reduced UIF production by 50% . UIF was found to be relatively resistant to heat and proteolytic enzymes in vitro . In addition UIF was capable of cytostatic or cytotoxic effects on tumor cells in tissue culture. UIF-like activity was found also in the plasma of tumor bearing mice. The biological role of UIF seems to be uncertain. Nevertheless it could interfere markedly with in vitro assays involving cell proliferation monitored by DNA-precursor uptake.

Allograft reactivity of mice against a radiation-induced lymphoma incompatible for the h-2k-ir regions of h-2.

Abstract B10.A(5R) mice reject 10 7 cells of a radiation-induced lymphoma of B10.A origin (LAF-17) incompatible for the H-2K-Ir regions of the H-2 complex. Most of the mice of B10.A(5R) strain succumb after a challenge of 10 4 cells of the same lymphoma. The immune response of B10.A(5R) mice against the tumor allograft has been studied 10–12 days after the challenge of 17 7 or 10 4 tumor cells. The inhibition of B10.A plaque-forming cells or radioactive LAF-17 cells injected intraperitoneally into untreated or pre-challenged B10.A(5R) mice was used to study the allograft reactivity of the mice. The results indicate that the mice challenged with 10 7 lymphoma cells showed a strong allograft reaction, whereas the allograft reaction of the animals injected with 10 4 cells was weak or absent, in spite of a rapid increase of antigen availability due to allogeneic tumor growth. In addition, it was observed that another radiation-induced lymphoma of B10.129(5M) origin was immunosuppressant for allogeneic mice and prevented their allograft response to high inocula of LAF-17 cells. It was concluded that the challenge of incompatible mice with a limited number of LAF-17 tumor cells did not provide initially an adequate antigenic stimulus and immunosuppressed the recipients. When the transplanted tumor reached the critical size necessary to promote an efficient allograft response, the host was incapable of rejecting the tumor and succumbed with generalized lymphoma.

Influence of presensitization with allogeneic lymphoma cells on the growth and response to therapy of radiation-induced lymphomas in mice

Congenic mice were sensitized with viableH-2-incompatible radiation-induced lymphomas (RIL), challenged with syngeneic RIL and treated with bis-chloroethyl-nitrosourea. Either enhancement or inhibition of RIL was found in presensitized mice, depending on the tumor-host system used.