Effect of a streptococcal preparation (OK432) on natural killer activity of tumour-associated lymphoid cells in human ovarian carcinoma and on lysis of fresh ovarian tumour cells

Perfusion drugs for non‑muscle invasive bladder cancer (Review)

The high recurrence rate and poor prognosis of non-muscle invasive bladder cancer (BC) are challenges that need to be urgently addressed. Transurethral cystectomy for bladder tumors is often combined with bladder perfusion therapy, which can effectively reduce the recurrence and progression rates of BC. The present review integrated and analyzed currently available bladder perfusion drugs, mainly including chemotherapeutic agents, immunotherapeutic agents and other adjuvant perfusion drugs. Bacillus Calmette-Guerin (BCG) perfusion was the pioneering immunotherapy for early BC and still ranks high in the selection of perfusion drugs. However, BCG infusion has a high toxicity profile and has been shown to be ineffective in some patients. Due to the limitations of BCG, new bladder perfusion drugs are constantly being developed. Immunotherapeutic agents have opened a whole new chapter in the selection of therapeutic agents for bladder perfusion. The present review explored the mechanism of action, clinical dosage and adverse effects of a variety of bladder perfusion drugs currently in common use, described combined perfusion and compared the effects of certain drugs on BC.

Enhancing the therapeutic efficacy of NK cells in the treatment of ovarian cancer (Review)

Ovarian cancer is a prevalent gynecological malignancy associated with a high mortality rate and a low 5‑year survival rate. Typically, >70% of patients present with an advanced stage of the disease, resulting in a high number of ovarian cancer‑associated deaths worldwide. Over the past decade, adoptive cellular immunotherapy has been investigated in clinical trials, and the results have led to the increased use in cancer treatment. Natural killer (NK) cells are cytotoxic lymphoid cells that recognize and lyse transformed cells, thereby impeding tumor growth. Thus, NK cells exhibit potential as a form of immunotherapy in the treatment of cancer. However, some patients with ovarian cancer treated with NK cells have experienced unsatisfactory outcomes. Therefore, further optimization of NK cells is required to increase the number of patients achieving long‑term remission. In the present review article, studies focusing on improving NK cell function were systematically summarized, and innovative strategies that augment the anticancer properties of NK cells were proposed.

Inhibition by streptococcal immunopotentiator OK432 of lymph-node metastasis in hamster cheek-pouch carcinoma with enhancement of tumour necrosis factor-alpha and interleukin-6 in serum

A well-known metastic model of human oral cancer employs 9,10-dimethyl-1,2-benzanthracene (DMBA) to induce hamster cheek-pouch carcinoma. Streptococcal immunopotentiator OK432 was studied here for its inhibitory effect on lymph-node metastasis in that model. The intraperitoneal administration of OK432, after excision of cheek-pouch tumours induced by DMBA, resulted in a marked reduction in the incidence of cervical lymph-node metastasis to 7%, a significant decrease beneath the rates observed for control animals not receiving OK432 (40%). OK432 also caused an increased in serum levels of tumour necrosis factor-alpha and interleukin-6 in tumor-bearing hamsters. These results suggest that the immune response may play an important part in the antimetastatic effects of OK432.

A trial of adjuvant chemoimmunotherapy with mitomycin C and OK-432 for stage III gastric carcinoma

We previously found that the ability to generate cytotoxic cells induced by in vitro activation of peripheral blood mononuclear cells (PBM) with OK-432, a bacterial immunopotentiator, was markedly increased following intravenous administration of a single dose of mitomycin C (MMC) in cancer patients. On the basis of this clinical finding, we designed a treatment regimen that consisted of MMC 12 mg/m2 intravenously on day 1 and OK-432 5 Klinische Einheit (KE) intradermally on days 6, 8, and 11, when the generation of OK-432 activated killer cells had been shown to be significantly augmented. Then, it was followed by long-term tegafur. Fifteen patients with stage III gastric carcinoma who had undergone curative resection were treated with the above regimen. The survival of these patients was significantly better than that of 26 comparable stage III patients concurrently treated with MMC 12 mg/m2 alone, followed by long-term tegafur (P less than 0.01). The results indicate that OK-432 combined with MMC may be effective against stage III gastric carcinoma, when these agents are used probably in an appropriate combination.

The streptococcal preparation OK-432 specifically augments the susceptibility of human urinary bladder tumor cells to autologous peripheral blood lymphocytes

The streptococcal preparation OK-432 was tested for its ability to enhance the susceptibility of fresh urinary bladder tumor (UBT) cells to autologous peripheral blood lymphocytes (PBL) in patients with UBT. PBL treated with OK-432 at 0.1 Klinishe Einheit (KE)/ml for 18 hours killed the human T24-lined UBT cells and freshly separated autologous UBT cells more efficiently than untreated PBL. Treatment of K562 erythroleukemia cells with OK-432 at 0.1 KE/ml for 18 hours had no effect on their susceptibility to lysis by fresh PBL. In contrast, treatment of T24 and fresh autologous UBT cells with OK-432 resulted in an enhancement of their susceptibility to PBL. The susceptibility of autologous UBT cells to both large granular lymphocytes (LGL) and T-lymphocytes was also enhanced by treatment of tumor cells with OK-432. Binding of PBL to T24 and fresh autologous UBT cells was also augmented by treatment of the tumor cells with OK-432. The frequency of binding of OK-432 to fresh UBT cells was positively correlated with the increased target sensitivity to autologous PBL. The inhibition of RNA synthesis in fresh UBT cells by OK-432 was also associated with the elevated susceptibility to autologous PBL. These results indicate that OK-432 activates the autologous tumor killing system through stimulation of effector cells and elevation of target susceptibility to effector cells in patients with UBT, and suggest that the OK-432-augmented target sensitivity to PBL may be oriented specifically to UBT cells and local immunotherapy with OK-432 may be remarkably beneficial in the treatment of UBT.

Production and characterization of tumor infiltrating lymphocyte clones derived from B16-F10 murine melanoma

The adoptive transfer of tumor infiltrating lymphocytes (TIL) in conjunction with recombinant interleukin-2 (rIL-2) for the treatment of advanced cancer has recently been under intense investigation. Despite extensive research, the precise surface phenotype of TIL remains to be fully defined. To elucidate this unsolved problem, we established 11 TIL clones derived from rIL-2 expanded TIL obtained from B16-F10 murine melanoma tumors. These clones could be divided phenotypically into four groups: CD8 (+) T-cell clones, natural killer (NK)-cell clones, NK-like CD8 (+) T-cell clones, and double negative T-cell clones. Functionally, CD8 (+) T-cell clones demonstrated specific cytotoxic activity against B16-F10 melanoma cells, whereas NK-cell clones and double negative T-cell clones demonstrated only non-specific cytotoxic activity against NK-sensitive YAC-1 cells. NK-like CD8 (+) T-cell clones showed dual cytotoxic activity. Clones T1 [a CD8 (+) T-cell clone] and T2 [an NK-like CD8 (+) T-cell clone] which had cytotoxic activity against B16-F10 melanoma cells, demonstrated a proliferative response against immunoblotted B16-F10 melanoma antigens, whereas clones T7 (an NK-cell clone) and T10 (a double negative T-cell clone), which had no cytotoxic activity against B16-F10 cells, demonstrated no proliferative response against them. Winn assays revealed that only the CD8 (+) T-cell clone (T1) had an antitumor effect in vivo, whereas the double negative T-cell clone (T10) and NK-like CD8 (+) T-cell clone (T2) stimulated tumor growth in vivo. Adoptive immunotherapy using tumor-specific, highly cytotoxic TIL clones may represent a useful future immunotherapeutic option for the treatment of human tumors.

Effects of the oral or intratumoral administration of OK432 on the immuno-reactivities of regional lymph nodes in gastric cancer patients

The effects of OK432, a streptococcal preparation, administered either orally (PO-OK432) or intratumorally (IT-OK432) on the immuno-reactivities of regional lymph nodes were investigated in gastric cancer patients. Although native lymph node lymphocytes (LNL) from untreated patients did not show any cytotoxicities against K562 and Raji cells, enhanced activities were found in LNL from patients administered OK432. Augmenting effects on the cytotoxicities of LNL by in vitro additional OK432, interleukin 2 or gamma-interferon were remarkable in the patients given IT-OK432. Moreover, the cytotoxicities of peripheral blood lymphocytes were augmented in vitro more strongly in patients given IT-OK432 than in those given PO-OK432. Flow cytometric analysis of LNL revealed a decrease in CD4+ cells by PO-OK432 and an increase in CD8+ cells by IT-OK432. An increase in CD4+2H4+ cells and a decrease in CD4+2H4- cells were observed in the patients given OK432, though CD8+CD11+ cells decreased by PO-OK432 while CD8+CD11+ cells increased by IT-OK432. Thus, it is suggested that LNL reactive to OK432 immunotherapy may differ between PO- and IT-OK432, and that the immunoreactivities of local lymph nodes and systemical immuno-reactivities may be highly potentiated by IT-OK432 rather than PO-OK432.

Changes in immunological parameters in lung cancer patients undergoing immunotherapy with streptococcal preparation OK-432

We have studied the immunological status of patients treated with streptococcal preparation OK-432. Two KE of OK-432 was injected intramuscularly once every week for more than three years unless the patients died. The natural killer (NK) activity in those patients who underwent curative surgery for lung cancer and had no sign of recurrence was significantly increased (P less than 0.01) during the OK-432 treatment. However, the NK activity in the patients who had persistent disease (non-resected cases, incompletely resected cases or recurrent cases) was not significantly increased in comparison with that before the immunotherapy. Also, in the cases with no clinical symptoms of recurrence, both the lymphoblastogenetic reactions to the mitogens and the IL-2 production were significantly enhanced (P less than 0.01) during the administration of OK-432. Reactions in the SU-PS (polysaccharide taken from the cell-wall fraction of the Streptococcus pyogenes SU strain and containing 7.2% of protein) skin-test appeared to significantly correlate with the immunological status of the patients under OK-432 therapy, but the PHA and PPD skin reactions showed no definitive enhancement. The survival rate of the patients whose SU-PS skin tests were positive during the OK-432 immunotherapy was significantly higher (P less than 0.01) than that of the patients with negative reactions.

Anti-tumor effect of intravesical instillation of OK432 against rat bladder tumors induced by N-butyl-N-(4-hydroxybutyl) nitrosamine

The anti-tumor effect of OK432 instilled into the bladder was evaluated in rat bladder tumors induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). In experiment I, the rate of the natural killer (NK) activity was determined with cells from spleen and mesenteric lymph nodes. Intravesical OK432 instillation enhanced NK activity; however, this activity was not dose-dependent and was not augmented by OK432 inoculation into the foot pad. In experiment 2, the therapeutic effect of intravesical OK432 instillation was examined in rat bladder tumors induced by BBN. OK432 was instilled weekly for six weeks. Rats given BBN for 10 weeks were divided into six groups: 1) control; 2) saline; 3) OK432 0.05 KE/ml; 4) OK432 0.05 KE/ml bladder instillation with 0.01 KE/ml foot pad inoculation; 5) OK432 0.05 KE/ml, every other week; and 6) OK432 0.5 KE/ml. Weekly OK432 instillation significantly reduced tumor weight and the incidence of tumor development; however, this inhibition was not dose-dependent and was not enhanced by OK432 inoculation into the foot pad. In rats given OK432 weekly, the augmentation of NK activity and increase in tissue infiltrating lymphocytes were significant. These results suggest that intravesical OK432 instillation is effective in the management of superficial bladder tumors. The study further emphasizes that the dose and method of administration are critical variables in determining the efficacy of immunotherapy.

Immunoresponse of tissue infiltrating lymphocytes in bladder tumors

Local immunocompetence was evaluated immunohistochemically in patients with bladder tumors before and after local injections of an immunomodulator. The subpopulations of tissue infiltrating lymphocytes (TIL) were examined by staining six serial sections with Leu4, Leu7, Leu10, LeuM3, OKT4, and OKT8 antibodies. T cells predominated over B cells in 19 of 25 bladder tumors. T cell infiltration was prominent around tumor cells, and it was marked in non-invasive tumors. B cells were rare in the stroma. In patients with low-stage tumors, OKT8 cells were more prominent than OKT4 cells. NK cells accumulated within cancer nests but their infiltration was scanty in invasive bladder tumors. Before surgery, immunomodulators (OK-432, IL-2) were injected intratumorally. Their administration resulted in marked increase of T and NK cells, irrespective of the stage of disease; there was a slight increase in B cells. These findings suggest that local immunosurveillance plays a role against bladder tumors. Further studies are required to elucidate host immune responses in the microenvironment of the cancer site, as well as the systemic immune reaction.

Production of interleukin 6 by human spleen cells stimulated with streptococcal preparation OK-432

The streptococcal preparation OK-432 was tested for the ability to stimulate human spleen leukocytes (SPL) for generation of interleukin 6 (IL-6). When SPL were cultured with OK-432 for 24 h in serum-free T medium, the cell-free supernatant induced production of IgM in the SKW6.CL-4 and IgG in the CESS human B cell line, while no such activity was detected in unstimulated SPL culture. The activity was neutralized by treatment with antiserum directed against B cell stimulatory factor 2 (BSF-2). An optimum production of BSF-2 was observed when SPL were stimulated with 10 micrograms/ml of OK-432. The culture supernatant also induced proliferation of IL-6-dependent murine hybridoma MH-60.BSF2 (hybridoma growth factor; HGF). It is thus evident that the molecule produced by OK-432-activated human SPL is BSF-2/HGF/IL-6. These results indicate that the antitumor agent OK-432 stimulates human spleen cells to produce IL-6.

Mechanism of immunotherapeutic activity of OK-432 in the treatment of peritoneal carcinomatosis

In this report the mechanism of therapeutic activity of OK-432 for the treatment of peritoneal carcinomatosis was investigated by correlating effector-cell augmentation with therapeutic activity in rats bearing MADB-106 carcinomatosis. Tumor cells were injected i.p. and the treatment with OK-432 was initiated 5 days later with 0.5, 1, 5 or 10 KE/animal of OK-432 injected i.p. semiweekly. Significant therapeutic activity was observed at all doses examined with greater prolongation of survival noted at the higher doses of OK-432. Animals treated with 0.5 KE/animal had a prolongation of the median survival time from 14 days for saline-treated animals to 17 days for the OK-432 treated animals (P less than 0.0008), while animals treated with higher doses had much longer periods of survival, some animals being tumor-free at 185 days. In the same studies, natural killer (NK) cell, lymphokine-activated killer cell, cytotoxic T lymphocyte, and macrophage tumoricidal/cytostatic activities were measured 7 days and 14 days following tumor injection (2 days and 9 days after initiation of immunotherapy). OK-432 had immunostimulatory activity in most of the assays of immune function examined and this correlated with host survival, including augmentation of peritoneal and peripheral blood cytotoxic T lymphocyte activity on day 14, peritoneal and alveolar macrophage activity on day 7 and day 14, as well as natural killer cell activity on day 14. These results suggest that the therapeutic doses are also immunomodulatory doses for the effector cells mentioned above. We suggest, therefore, that immunological monitoring may help to optimize treatment protocols for the treatment of peritoneal and perhaps pleural effusions with OK-432.

Killing of tumor cells with pleiotropic drug resistance by OK432-activated effector cells

The inactivate streptococcal preparation OK432 activates the cytotoxic function of natural killer (NK) cells. Moreover, it induces cytotoxic activity against freshly isolated tumor cells. The present study was aimed at assessing whether OK432-activated effector cells expressed cytotoxicity against tumor cells pleiotropically resistant to cancer chemotherapy agents. OK432-treated lymphoid cells killed the multidrug resistant (MDR) LOVO DX line as efficiently as drug sensitive parental LOVO N carcinoma line. Effector cells involved in killing MDR cells were low density large granular lymphocytes with NK functions. Activation of effector cells has the potential to complement conventional cytoreductive therapy by eliminating residual-tumor cells surviving and resistant to chemotherapy.

Immunocompetence of tissue infiltrating lymphocytes in bladder tumors

Tissue infiltrating lymphocytes (TIL) in bladder tumors have been assumed to be an expression of local host resistance against the tumor. We investigated the functional activity of TIL compared to peripheral blood lymphocytes (PBL). Isolation of TIL was performed using the enzyme cocktail treatment with Ficoll-Hypaque discontinuous gradient centrifugation. Analysis of lymphocyte subsets by flow cytometry demonstrated Leu 4, 43.6% (T cells); Leu 10, 10.5% (B cells) and Leu 7, 13.1% (natural killer (NK) cells) in TIL. The cytotoxic activity of TIL and PBL was tested in a four hour 51Cr-release assay. Myeloid K562 cells (NK sensitive), HT 1197 (bladder tumor) and fresh bladder tumors were used as target cells. The spontaneous NK cell activity of PBL was 23.7%, whereas that of TIL was only 3.5%. However, in vitro culture with IL2 induced a significant augmentation of NK activity in TIL as well as in PBL. On the other hand, the spontaneous lymphokine activated killer cell (LAK) activity of PBL and TIL was very low. IL2-cultured PBL and TIL exhibited the highest levels of lysis against fresh bladder tumors. Unlike PBL, IL2-induced cytotoxicity of TIL against autologous bladder tumors was higher than that against allogenic bladder tumors. Immunomodulators OK432 and Il2 were injected intratumorally during endoscopy. Analysis of the lymphocyte subsets in TIL showed an increase of T and NK cells following immunomodulator injection. Endoscopic injection of immunomodulators into bladder tumors augmented NK cell functional activity in TIL as well as PBL. These findings suggest that local immunosurveillance is directed against bladder tumors. Further studies are required to understand more fully the local and systemic host immune responses in cancer.

Immunotherapy of patients with terminal-stage malignant tumors with an immunopotentiator OK-432--a comparison of SU-PS test-responding and -nonresponding patients

Terminal malignant tumor cases were treated with immunopotentiator OK-432. The absolute numbers of neutrophils and lymphocytes and different lymphocyte subsets were determined, and SU-PS and PPD skin tests were also performed to monitor the immunologic status of each patient. The SU-PS test changed to positive in one-third of the patients 2-6 weeks after the start of therapy. The SU-PS responding patients showed an increase in lymphocytes and Leu II+ cells, and an elevation of the OK T4/T8 ratio 2 weeks later. In all patients from the responding group, the (OKIal+ - Bl+) cells decreased in the peripheral blood immediately after the positive change in the SU-PS test. In the SU-PS nonresponding group, the OKT4+ cells tended to decline with time, while the OKT8+ cells increased. That is, the OKT4/T8 ratio remained low throughout the test period. In the SU-PS responding group, OK-432 therapy prolonged the survival time.

Antitumor effect of the streptococcal preparation OK-432 in a murine model of ovarian cancer

The antitumor effects of the streptococcal preparation OK-432 were analyzed in a murine ovarian teratocarcinoma (MOT) model. Administration of OK-432 i.p. prevented tumor outgrowth in 75% of mice challenged with 10(3) MOT cells i.p. 24 h previously. Treatment was less successful in mice challenged with 10(4) or 10(5) cells, preventing tumor growth in 25% of the former and only 5% of the latter group. Tumor-challenged mice cured by injections of OK-432 were not rendered resistant to a subsequent challenge with 10(3) MOT cells 75 days after initial treatment. Only the i.p. route of administration was effective as i.v. OK-432 did not prolong survival of tumor-challenged mice. An antitumor response was detected as early as 24 h after i.p. treatment. This correlated temporally with an influx of neutrophils into the peritoneal cavity. Peritoneal cells obtained between 6 and 24 h after treatment were capable of lysing MOT targets in vitro. A single cell cytotoxicity assay demonstrated that peritoneal neutrophils, elicited by i.p. injection of OK-432, could bind to and lyse MOT targets. These data indicate that OK-432 is effective against small tumor cell inocula in this murine model of ovarian cancer and, furthermore, that the neutrophilic response into the peritoneal cavity plays a role in tumor rejection.

Modulation of the locomotory capacity of human large granular lymphocytes

The regulation of the migratory capacity of Percoll-purified large granular lymphocytes (LGL) into nitrocellulose filters was studied in a 2-hr assay with the use of modified Boyden chambers. Compounds that stimulate the natural killer cytotoxic function of LGL, such as interferons (natural beta, recombinant alpha A, recombinant hybrid alpha A/D, recombinant gamma), recombinant interleukin-2, and inactivated streptococci (OK 432), augmented the capacity of LGL to penetrate into filters spontaneously in the absence of chemoattractants in the lower compartment of the chamber. These compounds did not increase the LGL responsiveness to chemoattractants. Phorbol 12-myristate 13-acetate did not appreciably affect the locomotory capacity of LGL but augmented their cytotoxic activity. Thus the cytotoxic function and locomotion of LGL in response to biological response modifiers can be dissociated.

Inhibition of in vitro LAK generation by OK-432

The present study was designed to investigate the in vitro effect of OK-432 on interleukin-2-(IL-2) induced lymphokine activated killer (LAK) generation, and especially to test whether OK-432 can substitute for IL-2 or act in synergism with IL-2 for activation of cytotoxic lymphocytes. Surprisingly, our results showed that the addition of OK-432 to 4-day LAK activation cultures significantly inhibited both the generation of cytotoxic effectors to the natural killer (NK) resistant Daudi cell line and the proliferative responses of lymphocytes in a dose dependent manner. The inhibition of activation was total at 0.5 KE/ml of OK-432, a dose which was still effective in augmenting NK activity against K562. The addition of penicillin G potassium (PCGk), which is contained in OK-432 at a concentration of 134,700 units/mg of dried cocci, to the LAK culture system also inhibited LAK generation at equivalent concentrations as contained in the OK-432 preparation. This inhibition of LAK generation by OK-432 was significantly eliminated by dialysis of OK-432. These results indicated that the inhibition of LAK generation was partly due to PCGk contained in the OK-432 preparation, and that OK-432 did not act synergistically with IL-2 in standard LAK activation systems.

Limb-salvage procedures for osteosarcoma. An alternative to amputation

Amputation remains the standard surgical treatment for patients with osteosarcoma. However, in carefully selected patients, eradication of the primary lesion can be achieved by en bloc resection of the affected bone. Between 1963 and 1984, 77 patients with osteosarcoma of the extremity were seen. Forty-six patients were managed with combined treatment which included preoperative chemotherapy, operation and postoperative adjuvant chemotherapy between 1968 and 1984. We report the 11 patients in this group who underwent limb-salvage procedures.

Studies of the enhancement of natural cytotoxicity by the streptococcal immunopotentiator OK432

The immunopotentiator OK432, a product of Streptococcus pyogenes A3, enhanced the natural killer (NK) activity of unseparated human peripheral blood mononuclear cells (PBM) and separated, nonadherent lymphocytes (PBL) containing less than 0.5% contamination with monocytes. Following treatment with OK432, both unseparated and non-adherent cell preparations produced interferon (IFN) alpha and gamma and low levels of interleukin-2 (IL-2). However, in the presence of neutralising amounts of anti-IFN alpha and gamma antisera, the NK enhancing effect of OK432 was not fully inhibited. Filtered supernatants derived from OK432-treated PBM or PBL also enhanced the NK activity of fresh PBM. In this instance, in most experiments, the NK enhancing effect of supernatants (from non-adherent cells) was fully inhibited by anti-IFN antisera. However, in some experiments, enhancement of NK activity by anti-IFN antisera-treated supernatants was still found. It is suggested that the presence of IL-2 or, possibly, other as yet uncharacterized factors secreted following OK432 treatment, account for this residual enhancement of NK activity.

Effects of inactivated streptococci (OK-432) on macrophage functions in mice

The effects of inactivated streptococci (OK-432) on murine macrophage functions were investigated. In vivo treatment of peritoneal macrophages with OK-432 augmented the direct cytotoxic activity against TU5 tumor cells in a 48 h tritiated thymidine release assay. OK-432 also stimulated the rapid (6 h, 51Cr release) macrophage-mediated killing of Actinomycin D-sensitized WEHI 164 sarcoma cells. Moreover, the expression of la antigens on peritoneal macrophages was found to be greatly enhanced after in vivo treatment with OK-432. The immunomodulatory effects of OK-432 on macrophages functions may contribute to the antitumor activity of inactivated streptococci.

Activation of human blood lymphocytes and monocytes by the streptococcal preparation OK432: enhanced generation of soluble cytotoxic factors

The streptococcal preparation OK432 augments natural cytotoxicity of human blood lymphocytes and monocytes. It also enhanced the production of natural killer soluble cytotoxic factors (NKCF) when the effector cells interact with K562 cells. There was a good correlation between the OK432-induced enhancement of NK cell-mediated cytotoxicity and the released NKCF activity. OK432-pretreated monocytes secreted higher amounts of monocyte cytotoxic factors (MCF) than the untreated monocytes. With the monocytes the enhanced generation of MCF was not always accompanied by the increase in direct cell-mediated lysis of K562. OK432 treatment alone did not induce NKCF release from lymphocytes, and the presence of K562 in the culture was necessary. In contrast, monocytes generated MCF when exposed to OK432. In the supernatants of cocultures of OK432-activated effectors and K562 the NKCF and MCF activity was elevated two- to ten-fold. The OK432-induced augmentation of natural cytotoxicity exerted by lymphocytes and monocytes may be mediated through an increase in the synthesis, activation and/or release of NKCF and MCF.

Intrapleural administration of OK432 in cancer patients: augmentation of autologous tumor killing activity of tumor-associated large granular lymphocytes

Ten patients with carcinomatous pleural effusions were treated with single intrapleural (i.pl.) injections of the streptococcal preparation OK432 on day 0 and the effects of i.pl. OK432 on the lysis of fresh or cryopreserved autologous tumor cells isolated from the pleural effusions were observed on day 7. In eight patients tumor cells in the effusions had decreased or disappeared by day 7. The other two patients, however, had no clinical evidence of therapeutic benefit from i.pl. OK432. Effusion tumor cells were relatively resistant to lysis by autologous lymphocytes when tested in a 4-h 51Cr-release assay. Positive reactions were recorded for blood and effusion lymphocytes in two of ten untreated patients. Injection of OK432 i.pl. resulted in an induction or augmentation of cytotoxicity against autologous tumor cells and K562 in the effusions of seven of ten subjects by day 7. In contrast, autologous tumor killing activity of blood lymphocytes was not always modified by i.pl. OK432. Purification of large granular lymphocytes (LGL) by discontinuous Percoll gradient centrifugation enriched autologous tumor killing activity, with no reactivity in LGL-depleted, small T lymphocytes. Significant lysis of autologous tumor cells was observed with effusion LGL from seven of ten untreated patients. Seven days after i.pl. OK432 injection, effusion LGL expressed enhanced cytotoxicity against autologous effusion tumor cells, whereas T cells were still not cytotoxic to autologous tumor cells on day 7. The frequency of LGL among effusion lymphocytes was not altered by i.pl. OK432. Adherent effusion cells were not involved in lysis of autologous effusion tumor cells in either untreated or OK432-treated patients. In vitro treatment of blood and effusion lymphocytes with OK432 induced an enhancement of autologous tumor-killing activity in patients who subsequently responded to i.pl. OK432 treatment. OK432 augmented in vitro autologous tumor killing activity of LGL, whereas T cells failed to lyse autologous tumor cells even after in vitro activation with OK432. These results indicate that i.pl. administration of OK432 to cancer patients will result in an augmentation of autologous tumor killing activity of LGL in the pleural effusions, and that this could be responsible for the antitumor activity of i.pl. OK432 therapy.