In vitro cytotoxicity of peritoneal macrophages activated with Mycobacterium smegmatis

Functional alteration of macrophages by a slime-forming Lactococcus lactis ssp. cremoris

The effect of a slime-forming, encapsulated Lactococcus lactis ssp. cremoris KVS20 on macrophage function has been examined in vivo and in vitro in short-term studies. Peritoneal macrophages in which 21 to 34% of macrophage was presenting Fc gamma-receptor positive macrophages were elicited by intraperitoneal injection of 10 to 50 mg/kg of L. lactis ssp. cremoris KVS20. The peritoneal macrophage exhibited cytotoxic activity against Sarcoma-180 cells in which the maximum activity was obtained in macrophage from mice injected with 10 mg/kg on d 5. However, L. lactis ssp. cremoris KVS20 rendered the elicited macrophage cytotoxic in vitro. The cytotoxicity was significantly augmented by 6- and 24-h treatment at the concentration of 50 to 500 micrograms/ml. These results obtained in the short-term studies demonstrated that the antitumor activity of L. lactis ssp. cremoris KVS20 may be mediated through the enhanced cytotoxic activity of macrophage.

Effects of mouse testicular extract on immunocompetent cells

We investigated mouse testicular extract (TE) to clarify its biological functions in reproductive immunity. TE, at concentrations of 50-300 micrograms/ml, enhanced macrophage activities of spreading, glucose consumption, and cytostasis against a susceptible tumor cell line. On the other hand, TE inhibited concanavalin A (Con A)-induced T-cell blastogenesis in the dose range of 10-600 micrograms/ml. To elucidate the origin of TE, W/Wv mice, which genetically lack germ cells, were used. TE obtained from W/Wv mice enhanced the spreadability of macrophages and inhibited Con A-induced blastogenesis of T cells. The enhancement of macrophage spreading was only achieved by the interstitial fluid (IF), while the suppression of Con A-induced T-cell responses was detected in seminiferous tubule fluid (STF) as well as in IF. TE did not affect listerial antigen-specific responses of lymphocytes in vitro. These results suggest that TE has the capacity to regulate the biological responses associated with reproduction.

Immunogenicity of viable tumor cells. A comparison of xenogenized tumor cells and BCG-tumor cell mixtures

The immunogenicity of KMT-17 fibrosarcoma cells which had been xenogenized by infection with FV was compared to that of KMT-17 cells which had been admixed with BCG. We report here that 10(5) and 10(6) KMT-17 cells also grew progressively to kill rats, but when 10(5) KMT-17 cells were administered with BCG the tumor cells did not grow in the majority of rats. The strength of immunogenicity (ETD50), as measured by the number of immunizing cells required for a suppression of growth of 10(7) KMT-17 cells in 50% of the rats, was 2.1 X 10(3) for FV-KMT-17 and 36.3 X 10(3) for BCG + KMT-17. The tumor cell dose (LTD50) which was required to kill 50% of the rats immunized with 10(5) FV-KMT-17 was more than 10,000 times higher than that found in normal rats, whereas the number of tumor cells required to kill 50% of the rats immunized with the same number of BCG + KMT-17 was only 3,680 times higher than the amount found in normal rats. Thus the immunogenicity of FV-KMT-17 is much stronger than that of BCG + KMT-17. The difference in immunogenicity between the two vaccines was also observed in the tumor-neutralizing activities of spleen cells obtained from rats which had been immunized with both vaccines, as measured by a Winn assay. Moreover, the antitumor activity of spleen cells from rats immunized with FV-KMT-17 was concentrated in the carrageenan-resistant and plastic nonadherent cells, while that of spleen cells from rats immunized with BCG + KMT-17 was observed in carrageenan-sensitive and plastic adherent cells as well as in nonadherent cells. The involvement of different effector cells indicates that different mechanisms operate in the antitumor resistance in rats immunized with either FV-KMT-17 or BCG + KMT-17.

Macrophage activation by Lactobacillus casei in mice

Effects of Lactobacillus casei YIT 9018 (LC 9018), which has antitumor activities against allogeneic and syngeneic murine tumors, on macrophage functions were examined. By intraperitoneal (i.p.) injection of LC 9018, acid phosphatase activity and phagocytic activity of peritoneal macrophages were enhanced significantly compared with those of normal peritoneal macrophages. The phagocytic activities showed peaks 2-3 days after the LC 9018-injection. LC 9018 accelerated the phagocytic function of the reticuloendotherial system in ICR mice tested by the carbon clearance test. The cytostatic activity of peritoneal exudate cells (PEC) induced by i.p. injection of LC 9018 into C57BL/6 mice against EL4 cells was also enhanced. On the other hand, PEC induced by L. fermentum YIT 0159, which has no antitumor activity, did not have cytostatic activity. These observations showed that LC 9018 was able to activate macrophages in mice.

Mouse-strain difference in immunoprophylactic and immunotherapeutic effects of BCG on carcinogen-induced autochthonous tumors

The prophylactic and therapeutic effects of BCG on the tumors induced by 3-methylcholanthrene (MCA) were studied comparatively between two inbred mouse strains, SWM/Ms and C3H/He, the first tumor appeared 5 weeks after MCA and the cumulative tumor incidence reached almost 100% within 20 weeks. On the other hand, the first tumor appeared 8 weeks after MCA in SWM/Ms, the number of tumor-bearers increased more slowly than in C3H/He, and the final tumor incidence (at 30 weeks) was about 90-80%. Single subcutaneous injection with BCG 2 weeks prior to MCA significantly protected SWM/Ms from tumor development, but not in C3H/He. These tumors, once appeared grew progressively and killed the hosts equally in both the strains. Intratumor (i.t.) injection with BCG showed more or less therapeutic effects in SWM/Ms; most tumors regressed or retarded after BCG. The time period after tumor-appearance to tumor-death was prolonged in most of SWM/Ms mice given i.t. injection with BCG, except a few mice that died earlier than non-treated controls after BCG. Contrary, no therapeutic effect of i.t. injection with BCG was observed in C3H/He. different host responses to BCG between SWM/Ms and C3H/He were found by the peritoneal macrophage disappearance test and the footpad reaction test; SWM/Ms was a high-responder to BCG and C3H/He was a low-responder. The marked differences between SWM/Ms and C3H/He in prophylactic and therapeutic effects of BCG on the autochthonous tumors were discussed in terms of difference of the host immune response to BCG that is defined genetically.