Maury Rosenstein

REGRESSION OF A DISSEMINATED SYNGENEIC SOLID TUMOR BY SYSTEMIC TRANSFER OF LYMPHOID CELLS EXPANDED IN INTERLEUKIN 2

Anomalous killer cells are Thy-1(+) blasts that are cytolytic to the natural killer (NK)-sensitive lymphoma YAC-1, and that can be detected early (day 3-4) in the period preceeding the allospecific cytotoxic T lymphocyte (CTL) response in (CBA x A)F1 {arrow} C57B1 mixed leukocyte culture (MLC). We have investigated the origin and nature of anomalous killing (AK), with special emphasis on its relation to NK-and allospecific CTL-activity. AK was shown to be distinct from the previously described “NK(c)-cells” induced by cultivation in fetal calf serum (FCS)-supplemented medium when these two reactivities were examined in parallel. AK was detected in either FCS- or normal mouse serum (NMS)-supplemented allogeneic MLC, indicating that the response was not dependent on mitogenic or antigenic properties of heterologous serum. In addition to several H-2-incompatible combinations, AK was also observed in an Mls-incompatible (but H-2 compatible) and two F(1)- antiparental MLC responder/stimulator combinations. AK cells showed a similar selectivity pattern to NK cells, as demonstrated in cold target inhibition and direct cytotoxicity assays using variant or interferon-modulated YAC-1 cells with low expression of NK target structures. The AK-cells were NK- 1.2(-/weak). Thy-l.2(+), although they seem to be derived from non-adherent radiosensitive cells which are closely related, if not identical, to NK-cells (NK-1.2(+). Thy-l.2(-/weak)), as they could not be readily induced in responder populations with low NK-activity but normal allospecific CTL potential. Conversely, an in vivo thymectomy protocol or treatment of normal spleen cells with monoclonal anti-Thy-1.2 + C reduced the allospecific CTL response drastically but did not affect the AK response. Anomalous killers were not observed when MLC were prepared with responder as well as stimulator cells devoid of mature T cells. In such a combination, the AK response could be partially restored by the addition of irradiated +/nu (but not nu/nu) responder cells to the cultures. When normal (non-nude) spleen cells were used as responders, induction of AK did not require the presence of T cells in the stimulator population, whereas the removal of adherent and phagocytic cells from stimulators abrogated the response. Taken together, the results suggest that AK represents activation, blast transformation, and surface marker modulation of NK cells induced by alloantigen-stimulated T cells, resulting in Thy-1(+) cytolytic cells with similar properties to those described for NK lines, Although AK cells may be regarded as a more T cell-like NK phenotype, their induction is neither necessary, nor sufficient for generation of specific CTL in MLC.

Adoptive chemoimmunotherapy of a syngeneic murine lymphoma with long-term lymphoid cell lines expanded in T cell growth factor

SummaryRecently techniques have been developed for the long-term growth of cytotoxic T-lymphoid cells in vitro with T cell growth factor (TCGF). We have investigated the use of these in vitro-expanded T cells for the immunotherapy of a disseminated syngeneic murine FBL-3 lymphoma. In this model, mice with disseminated tumor were treated on day 5 with 180 mg cytoxan/kg and then 5 h later were given lymphoid cells IP. In vivo-immunized lymphocytes resulted in significantly improved survival in three of three experiments, curing 52% of 38 animals, compared with treatment with cytoxan alone (0 of 31 cured) or cytoxan plus unimmunized cells (0 of 40 cured) (P<0.0005). In vivo-immunized lymphocytes were re-exposed to FBL-3 tumor in vitro for 5 days in complete medium (CM) or lectin-free TCGF (LF-TCGF). Both groups showed significantly improved survival in six of six experiments. Cytoxan cured 17% of 66 animals, while cytoxan plus normal lymphocytes after IVS cured 6% of 47 animals. In vivo-immunized cells resensitized in vitro to FBL-3 in CM or LF-TCGF cured 82% of 50 animals (P<0.001) and 72% of 61 animals (P<0.001), respectively. Cells from in vivo- and in vitro-sensitized lymphocytes exhibited no cytotoxicity in our in vitro 51Cr-release assay; expansion of these cells resulted in significant specific lysis of fresh FBL-3 targets. Adoptive transfer of immune lymphocytes resensitized to FBL-3 tumor in vitro and expanded in LF-TCGF conferred a significant survival benefit (P<0.001, curing 7 of 27 animals) compared with all controls. These expanded cells were then continuously grown in LF-TCGF for 2 1/2 months. Again, in vivo-immunized lymphocytes resensitized to FBL-3 tumor and expanded in LF-TCGF for 2 1/2 months cured 56% of the animals with disseminated tumor, significantly prolonging survival over that recorded in any control group (P<0.0002). Irradiation of these same cells totally abolished their efficacy. Clones were generated from IVS and continuously grown in LF-TCGF. Two of these clones were very cytotoxic for fresh FBL-3 (>4,000 lytic units/106 cells). When adoptively transferred to mice in this chemoimmunotherapy model these cytotoxic clones significantly enhanced survival over that recorded following treatment with cytoxan alone (P<0.00001), though prolongation of survival was small. Implications of these results for application of these techniques to other less antigenic tumors and human cancers are discussed.

Clonal analysis of the lymphoid cells mediating skin allograft rejection. Mediation of graft rejection in vivo by cloned Lyt-1+2− proliferative, noncytotoxic long-term cell lines

Studies were undertaken to elucidate the cellular basis of skin allograft rejection mediated by long-term cultured cell lines and clones. The adoptive transfer, in vivo, of in-vitro-sensitized cells, from B6AF1 anti B10.BR or from C57BL/6 anti DBA/2 cultures, and expanded eight-fold to ten-fold for one week in lectinfree interleukin 2 (LF-IL-2) were able to mediate specific skin allograft rejection. These same cells lost the ability to mediate accelerated skin graft rejection when they were expanded more than 100-fold during three weeks of culture in LF-IL-2 even though these cultures mediated high levels of specific in vitro cytotoxicity for the appropriate allosensitizing cells. When Lyt-2+ cells were depleted using monoclonal antibodies and complement prior to in vitro sensitization and expansion in LFIL-2, these cells lines retained the ability to mediate skin allograft rejection in vivo when expanded more than 100-fold for three culture generations in vitro. These latter lines were greatly enriched for Lyt-1+2- cells and had little or no cytolytic activity, but they retained specific in vitro proliferative responses to the sensitizing alloantigen. Several Lyt-1-2+ cloned longterm lymphoid cell lines with high levels of specific cytolytic activity against the sensitizing alloantigen were derived and none was capable of mediating the accelerated rejection of skin grafts in vivo. However, cloned lymphoid cell lines that were phenotypically Lyt1+2- and were capable of proliferating when in contact with specific alloantigen, but were not cytolytic, were capable of mediating the accelerated rejection of skin grafts in vivo both in irradiated mice and in nude mice. These studies demonstrate that skin allograft rejection can be mediated by Lyt-1+2- cell lines with specific in vitro proliferative activity to alloantigen although Lyt-1-2+ cell lines with cytolytic but not proliferative activity to alloantigen in vitro are ineffective in mediating graft rejection in vivo. Specific proliferative activity and no cytolysis appears to be a good in vitro correlate of the in vivo activity of long-term cultured cell lines.

Optimal methods for generating expanded lymphokine activated killer cells capable of reducing established murine tumors in vivo

The systemic administration of lymphokine activated killer (LAK) cells and recombinant interleukin-2 (RIL-2) is effective in reducing the number of established pulmonary and hepatic metastases from multiple murine tumors and has recently been shown to be effective in mediating the regression of metastatic cancer in humans as well. The generation of sufficient numbers of LAK cells for the effective therapy of human tumors remains a major obstacle to the widespread application of this immunotherapeutic approach. We have thus studied methods for the in vitro expansion of LAK cells effective in immunotherapy. Our previous studies used LAK cells generated in culture with RIL-2 for 3 days. LAK cells cultured in RIL-2 for 5 or 7 days were not significantly different from cells cultured for 3 days either in the number of cells obtained, their in vivo cytotoxicity or their in vivo therapeutic effectiveness. When day 3 LAK cells were transferred to fresh culture medium containing 1000 U/ml of RIL-2, a highly reproducible expansion of these cells was obtained. By day 5, cell numbers expanded 9.6 +/- 0.8-fold (mean +/- SEM; n = 36) and by day 8, cells expanded 15.1 +/- 1.0-fold (n = 19). In 4 h 51Cr release assays against fresh tumor target cells, day 3 LAK cells had a mean of 13 lytic units/10(6) cells in 24 experiments. Day 5 expanded LAK cells had a mean of 30 lytic units/10(6) cells in 13 experiments (P less than 0.05 compared to day 3 LAK cells) and day 8 expanded LAK cells had a mean of 11 lytic units/10(6) cells in 6 experiments (P = NS compared to day 3 LAK cells) When day 5 and day 8 expanded LAK cells were infused in vivo with RIL-2, they were found to significantly reduce the number of experimentally induced pulmonary metastases as effectively as non-expanded conventional day 3 LAK cells. Similar findings were documented in experiments against hepatic metastases. These experiments demonstrate that LAK cells could expand a mean of 15-fold in vitro in RIL-2 and maintain their anti-tumor therapeutic effectiveness when adoptively transferred. These experiments suggest methods for generating increased numbers of cells for use in the adoptive immunotherapy of human cancers and may substantially reduce the need for repeated leukophereses of cancer patients undergoing this therapy.

Simplified techniques for the isolation of alloreactive cell lines and clones with specific cytotoxic or proliferative activity

A rapid method is described for the isolation of alloantigen specific proliferative and cytotoxic clones from primary mixed lymphocyte cultures (MLC). To raise cell lines and clones with specific alloantigenic proliferative activity in vitro, responder splenocytes were depleted of Lyt-2+ cells by monoclonal antibody and complement prior to in vitro sensitization. This procedure resulted in cultures highly proliferative to alloantigen with little or no lytic activity after expansion in interleukin-2 (IL-2). Subsequent cloning of lymphocytes from Lyt-1+ enriched allosensitized cultures by limiting dilution led to proliferative clones in extremely high yield, while cloning from nondepleted allosensitized cultures led to cytotoxic clones in high yield. Furthermore, conditions of high antigen and low IL-2 concentration favor the growth of proliferative cells while high IL-2 concentrations favored the growth of cytotoxic cells. These experiments indicate that selection for cytotoxic or proliferative clones may be enhanced by specific depletion of T cell subpopulations and by alteration of culture conditions.

The Use of Lymphoid Cells Expanded in IL-2 for the Adoptive Immunotherapy of Murine and Human Tumors

The adoptive immunotherapy of cancer refers to the transfer, to the tumor-bearing host, of immunologically competent cells capable of mediating responses against tumor. Specific adoptive immunotherapy is a theoretically attractive approach to the treatment of tumors although few examples exist of the effective treatment of established syngeneic solid tumors using this modality. Early reports from Delorme and Alexander (1964) claimed that thoracic duct lymphocytes from immunized rats as well as lymphocytes from immunized xenogeneic animals (Alexander et al., 1966) could mediate the regression of solid methylcholanthrene-induced sarcomas. Borberg et al. (1972) treated mice bearing the Meth-A sarcoma with up to 4 × 109 immunized syngeneic lymphocytes and succeeded in causing the regression of established tumors. Using the Meth-A tumor, but an alternative method of immunization, Berendt and North (1980) have demonstrated that the intravenous infusion of sensitized T cells from immune donors could cause complete regression of established tumors growing in a T-deficient host. They also showed that infusion of splenocytes from tumor-bearing donors could inhibit this regression, suggesting that suppressor T cells existed in the tumor-bearing host. Fernandez-Cruz et al. (1980) showed that intravenous infusion of immune lymphocytes was capable of curing rats bearing a subcutaneous tumor, and Smith et al. (1977) showed that immunized peritoneal exudate cells from syngeneic guinea pigs were capable of curing guinea pigs with established line 10 hepatoma.