Anticancer effect and immunologic response to xenogeneic embryonic proteins in mice bearing Ehrlich solid carcinoma

AIM

To investigate anticancer and immunologic effects of chicken embryonic proteins (CEP) in mice bearing Ehrlich solid carcinoma.

MATERIALS AND METHODS

The study was carried out on male Balb/c mice bearing Ehrlich solid carcinoma. The immunizations were performed after the tumor transplantation. The immune status was assessed on days 7, 14, 21 and 28 after the tumor challenge. Cytotoxic activity (CAT) of macrophages (Mph), natural killer cells (NK), cytotoxic T-lymphocytes (CTL) and blood serum, as well as the influence of the blood serum on immune cells activity was checked in MTT-assay; Mph's cytochemical activity was tested in NBT-assay; Ehrlich antigen-specific or CEP-specific antibodies were detected in ELISA-assay; medium size circulating immune complexes (CIC) were detected in reaction of 4.5% polyethylene glycol precipitation.

RESULTS

The immunization resulted in tumor growth suppression and significant 25.64% prolongation of the survival time. In both control and immunized mice with transplanted tumors antibodies specific to Ehrlich carcinoma antigens and to CEP were detected, but antibody response was more balanced in the treatment group. In the treatment group both cytochemical and CAT of Mph was moderately activated and well preserved until late stages of tumor development; CAT of NK and CTL remained in the range of the intact mice until day 28 after the tumor transplantation. The immunized mice were well protected from accumulation of CIC and suppressive activity of autologous blood serum.

CONCLUSION

Collectively, our data indicate that CEP can elicit immunomodulating and immunoprotecting effects sufficient to provide tumor growth inhibition. The further elaboration of a xenogeneic anticancer vaccine based on CEP is warranted.

Anticancer effectiveness of vaccination based on xenogeneic embryo proteins applied in different schedules

THE AIM

To evaluate anticancer activity of vaccination with chicken embryo proteins (CEP) applied in different schedules.

MATERIALS AND METHODS

C57Bl mice were vaccinated with CEP before (prophylactic schedule) or after (different therapeutic schedules with or without preliminary tumor removal) the Lewis lung carcinoma cells transplantation. The latent period of tumor development, tumor volume and metastasis rate were evaluated.

RESULTS

Potent antimetastatic effect of CEP-based vaccination was seen in case of therapeutic regimen after primary tumor removal. The metastasis inhibition index (MII) reached 96.9 and 97.8% on 18(th) and 34(th) day after tumor removal, respectively. When CEP vaccination was performed in the settings of therapeutic regimen without primary tumor removal the anticancer effect was evident only if vaccinations started as early as 24 h after the cancer cells injections. The highest MII achieved in such condition was 77.6%, tumor volume in the group of vaccinated animals was by 53.1-42.1% lower than in the control tumor-bearing mice. CEP vaccination before tumor challenge (prophylactic immunization) led to a statistically significant prolongation of the latent period of tumor development, a reduction of tumor volume (35.8-48.8% compared to control unvaccinated mice) and a marked inhibition of metastasis (MII was 71.1%).

CONCLUSION

Vaccination based on CEP exhibited both prophylactic and therapeutic anticancer effects. The last one is more pronounced when the vaccination starts shortly after the primary tumor resection.

The anticancer efficiency of the xenogeneic vaccine and the indication for its use

AIM

To investigate the anticancer efficiency of the xenogeneic vaccine in different tumor models and to assess the possibility whether level of antibodies (Ab) specific for vaccine's proteins can be used as an indication for its use.

METHODS

Mice with Lewis lung carcinoma (LLC), Ehrlich carcinoma (EC) or Sarcoma 37 (S37) were immunized with a xenogeneic anticancer vaccine based on chicken embryo proteins (CEP) and its anticancer activity was examined. The level of specific Ab in the blood serum of non-immunized tumor-bearing mice was studied by ELISA.

RESULTS

CEP application statically significantly inhibited the growth of LLC (the index of tumor growth inhibition was 42.10-53.13% depending on the day of tumor growth); vaccinated mice with EC showed significant tumor growth inhibition and life prolongation by 34.48%. Among mice with S37, there was noticed no antitumor effect. The number of tumor-bearing non-immunized mice which have had pre-existing CEP-specific Ab did not differ depending on the tumor model. The level of CEP-specific Ab among mice with LLC and EC increased with the growth of the tumor volume, but it decreased among mice be-aring S37. Probably, the low level of CEP-specific Ab alongside huge tumor burden shows it is futile to apply the CEP-based vaccine.

CONCLUSION

Different tumor strains vary in their susceptibility to CEP-based vaccine. Probably, the low level of CEP-specific Ab when a tumor burden is huge shows it is futile to apply the CEP-based vaccine. Key Words: xenogeneic anticancer vaccine, chicken embryo proteins anticancer activity, Lewis lung carcinoma, Ehrlich carcinoma, Sarcoma 37, CEP-specific antibodies.

[Influence of probiotic subalin on efficiency of antitumor vaccine]

Preparation subalin created on the basis of a recombinant strain of B. subtilis 2335/105 containing the gene of synthesis of human a-2-interferon has been tested in the experiment for its ability of increasing the efficiency of antitumor vaccine prepared from syngenic tumor cells and cytotoxic lectin--the metabolism product of the strain of B. subtilis B-7025. On the models of Lewis lung carcinoma of C57B1 mice and sarcoma-37 of Balb/c mice it was shown that the complex use of the antitumor vaccine and subalin makes for the more efficient tumor growth suppression and survival of treated animals as compared with the separate use of autovaccine or subalin. The prospects and expediency of the complex use of vaccine and subalin at malignant tumors immunotherapy were established.

[The antitumor activity of vaccines obtained by using a culture broth filtrate of Bac. mesentericus AB-56 or antibiotic AB-56]

The possibility of the purified antibiotic, extracted from the Bac. mesentericus AB-56 culture liquid, application for the antitumoral vaccine preparation and standardization was established in experiment, conducted on the mice of Balb/c line.