Prolactin response of NK cells, but not of LAK cells, is deficient in patients with carcinoma of oral cavity and during aging

Macrophage inflammatory protein (MIP)1alpha and MIP1beta differentially regulate release of inflammatory cytokines and generation of tumoricidal monocytes in malignancy

The C-C chemokines, macrophage inflammatory protein (MIP)1alpha and MIP1beta are potent chemoattractants for the monocytes, which form an important component of the stroma of tumor tissue and may regulate tumor growth and associated inflammation. We examined the role of MIP1alpha and MIP1beta in inducing the release of inflammatory cytokines and the generation of tumoricidal monocytes from the peripheral blood monocytes (PBM) of healthy women and patients with carcinoma of breast (CaBr). Interleukin-1 (IL-1) and tumor necrosis factor (TNF) alpha release by the PBM was markedly stimulated by MIP1alpha in CaBr patients, but only marginally so in healthy women. In contrast, MIP1beta stimulated the release of these cytokines by the PBM of healthy women, but failed to do so in CaBr patients. MIP1alpha, but not MIP1beta, synergized with LPS in inducing the release of IL-1 from the PBM of both healthy women and CaBr patients. Both MIP1alpha and MIP1beta augmented respiratory bursts in PBM and generated tumoricidal PBM that killed T24 cells, MIP1alpha being more effective in CaBr patients and MIP1beta in healthy women. IFN-gamma co-stimulated and IL-4 suppressed MIP1alpha and beta-induced cytotoxicity in PBM. The synergy of IFN-gamma was more marked with MIP1alpha than with MIP1beta. The differential effects of MIP1alpha and MIP1beta on the PBM of healthy women and CaBr patients co-related with the levels of expression of CCR1 and CCR5 in these monocytes. The expression of CCR5 was higher than that of CCR1 in the PBM of healthy women and the PBM of the CaBr patients showed overexpression of CCR1 and downregulation of CCR5.

Immunostimulatory neem leaf preparation acts as an adjuvant to enhance the efficacy of poorly immunogenic B16 melanoma surface antigen vaccine

Immunogenecity of the poorly immunogenic B16 melanoma cell surface antigen (B16MelSAg) was enhanced by combining B16MelSAg with NLP in C57BL/6 mice, as evidenced by ELISA and flow cytometry. NLP was as effective as Freund's complete and incomplete adjuvant to generate antibodies recognizing the B16MelSAg. The NLP generated antibody was a gamma globulin with a subtype of IgG1. Splenic lymphocytes from B16MelSAg+NLP treated mice proliferated more rapidly in vitro when stimulated by specific (B16MelSAg) and nonspecific (ConA) stimulators, in comparison to the proliferation detected in B16MelSAg and NLP treated groups. Vaccination of mice with B16MelSAg+NLP more efficiently prevented the growth of B16 melanoma tumor than mice immunized with B16MelSAg or NLP alone. In another experiment, the immune sera (B16MelSAg+NLP) was mixed with B16Mel tumors and injected subcutaneously into syngenic C57BL/6 mice. Tumor burden was less in mice receiving a tumor along with B16MelSAg+NLP generated immune sera than other groups. The B16MelSAg+NLP generated immune sera induced antibody dependent cellular cytotoxicity specifically towards B16Mel tumor cells in vitro. We concluded that NLP might be a potential immune adjuvant for inducing active immunity towards tumor antigens.

Antitumor effects of recombinant human prolactin in human adenocarcinoma-bearing SCID mice with human NK cell xenograft

To survey the immune regulatory function of recombinant human prolactin (rhPRL) and its potential application in adoptive immunotherapy, CB17-SCID mice were loaded with human colon adenocarcinoma HT-29 cells (5 x 10(5) cells/mouse, i.p.) 24 h before adoptive transfer with the purified human NK cells followed by rhPRL injection (10 mug/mouse, every other day for a total of 10 injections). Upon analysis, rhPRL did not exert any direct inhibitory effects on HT-29 cells but slightly improved the tumor cell growth both in vitro and in vivo. After SCID mice were reconstituted with human NK cells, rhPRL improved the antitumor effects of human NK cells in HT-29-bearing SCID mice, showing a prolonged survival from 70.4 to 112.1 days, and the increased survival rate from all died to 40% survival for more than 160 days. rhPRL improved the proliferation of human NK cells with or without PHA stimulation. rhPRL also directly enhanced the cytotoxicity of human NK cells against HT-29 tumor cells in 4-h coculture. The supernatant of rhPRL-stimulating NK cells inhibited the proliferation of HT-29 cells through, at least partly, the interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the supernatant. Thus, rhPRL administration in HT-29 tumor-bearing SCID mice promotes the antitumor effects of adoptively transferred NK cells.

Neem (Azadirachta indica) leaf mediated immune activation causes prophylactic growth inhibition of murine Ehrlich carcinoma and B16 melanoma

Conditional growth inhibition of murine Ehrlich carcinoma (EC) and B16 melanoma (B16Mel) was observed, following treatment of mice (Swiss and C57BL/6) with aqueous extract of neem (Azadirachta indica) (1 unit/mice/week for 4 weeks) either before or after inoculation of 1 x 10(6) tumor cells. Tumor inoculation after weekly injections for 4 weeks with neem leaf preparation (NLP) induced significant reduction of tumor growth (both EC and B16Mel) and increased survivability of mice. On the other hand, NLP treatment after tumor inoculation demonstrated no tumor growth inhibition in the NLP treated group in comparison to the PBS treated control. No direct cytotoxic effect of NLP towards EC and B16Mel tumor cells was observed in vitro. The spleen cells of NLP treated mice when mixed with inoculum of B16Mel tumor cells and injected into a group of mice, tumor growth was found to be significantly reduced and survivability of the tumor hosts increased remarkably in comparison to mice inoculated with tumor along with normal spleen cells. Concanavalin A (ConA) induced proliferation of lymphocytes from NLP treated mice was significantly higher than the lymphocytes of untreated mice. In in vitro, NLP by itself had no proliferative effects on lymphocytes but it co-stimulated ConA induced mitogenesis. NLP induced lymphocytosis as evidenced by increased lymphocyte count in blood as well as spleen. Flow cytometric evidence suggested that increase in CD4+ and CD8+ T cells accounted for lymphocytosis. The conditional tumor growth retardation, observed in mice treated with NLP before tumor inoculation, may be regulated by NLP mediated immune activation, having prominent role in the cellular immune function of the tumor host.

Recombinant human prolactin improves antitumor effects of murine natural killer cells in vitro and in vivo

OBJECTIVE

To verify the effect of prolactin on natural killer (NK) cells in vivo and its implications for NK cell immunotherapy.

METHODS

Recombinant human prolactin (rhPRL; 30 microg, i.p.) was administered to BALB/c mice and severe combined immunodeficiency (SCID) mice 1 day before harvesting splenocytes for (51)Cr release assay to examine the effects of rhPRL on NK cells of normal mice. rhPRL (10 microg, i.p., every other day for a total of 5 injections) was administered to BALB/c mice after syngeneic bone marrow transplantation (SBMT) to determine its effects on NK cell reconstitution. CT26 tumor cells were injected into BALB/c mice intravenously on day 0, and interleukin (IL)-15-cocultured activated syngeneic NK cells (IL-15-NK) from SCID mice were intravenously injected into tumor-bearing BALB/c mice on day 1. The improvement of antimetastasis effects and survival of tumor-bearing mice by rhPRL were checked.

RESULTS

BALB/c and SCID mice receiving one rhPRL injection exhibited a significant increase in cellular cytotoxicity against YAC-1 target tumor cells; the specific lysis was enhanced from 12.5 to 17.3% in BALB/c mice and from 27.8 to 51.2% in SCID mice. BALB/c mice continuously receiving rhPRL injections exhibited significant increases in NK cell (DX5-positive) contents and cellularity in both the bone marrow and spleen in the SBMT model. The bone marrow NK cell contents were improved from 1.53 to 3.13% after rhPRL injection. NK cells from SCID mice were then cultured with recombinant human IL-15 (rhIL-15; 6000 IU/ml), rhPRL (10 ng/ml) or rhIL-15 plus rhPRL for 25 days. The cytotoxicity and cellularity were enhanced by rhPRL when tested on day 10, when comparing the rhIL-15 plus rhPRL group with the rhIL-15 group or rhPRL group, respectively. In the adoptive cellular immunotherapy study, the IL-15-NK plus IL-15 plus rhPRL group showed significantly lower numbers of lung metastases and longer survival than the IL-15-NK plus IL-15 group; the mean survival interval was prolonged from 31.5 to 53.7 days.

CONCLUSION

These results indicate that rhPRL is possibly an important regulator of NK cells and a potential biologic product for immunotherapy.

Prolactin regulates antitumor immune response through induction of tumoricidal macrophages and release of IL-12

The involvement of PRL in regulating monocyte/macrophage functions is suggested by the presence of PRL-Rs in these cells. Here, we show that PRL, though it failed to activate mouse peritoneal resident macrophages (RMs), acted as a second signal and activated mouse peritoneal inflammatory macrophages (EMs) to a tumoricidal state. The cytotoxicity of mouse tumor-associated macrophages (TAMs) isolated at day 1 of tumor (Ehrlich ascites carcinoma, EAC) growth was enhanced by PRL. However, with progression of tumor growth, TAMs became nonresponsive to the hormone. PRL-induced killing of P815 target cells by EMs and TAMs was independent of TNF but correlated with the hormone-induced augmentation of NO2(-) and O2(-) release in these macrophages. Administration of PRL in vivo inhibited EAC growth and augmented NO2(-) release by TAMs. PRL synergized with the TH1 cytokine IFN-gamma, a known activator of macrophages, in inducing tumor killing and release of NO2(-) from EMs and TAMs. The hormone might activate macrophages at least partially, through the release of IFN-gamma as anti-IFN-gamma blocked IFN-gamma- as well as PRL-induced cytotoxicity in EMs. The TH2 cytokine IL-4 suppressed PRL-induced activation of macrophages. PRL induced release of IL-12 from EMs also, which suggested that the hormone might drive the TH1 response through IL-12. Our observations further suggest that PRL alone and in synergy with IFN-gamma, released through induction of IL-12, may generate tumoricidal macrophages and thus regulate the antitumor immune response of tumor hosts.

Up-modulation of interferon-gamma mediates the enhancement of spontanous cytotoxicity in prolactin-activated natural killer cells

Prolactin (PRL) has been shown to participate in lymphocyte activation. In particular, the constitutive natural killer (NK) and the lymphokine-activated killer (LAK) cytotoxicity of CD56+ CD16+ cells is increased by its physiological to supraphysiological concentrations. As PRL has been shown to up-regulate the production of interferon-gamma (IFN-gamma) by peripheral blood mononuclear cells, we studied its effect on IFN-gamma production by NK cells as a possible mechanism of autocrine activation of cytotoxicity. Released and intracellular IFN-gamma, as well as IFN-gamma mRNA expression, were increased by pituitary and recombinant human PRL, which stimulated optimal NK and LAK cytotoxicity. Treatment with blocking anti-IFN-gamma monoclonal antibody (mAb) selectively affected PRL-increased killing of K562 targets, demonstrating that PRL-mediated enhancement of spontaneous cytotoxicity depends, at least in part, on up-regulation of IFN-gamma.

Absence of prolactin gene expression in colorectal cancer

AIMS

Previous studies documenting hyperprolactinaemia in patients with colorectal cancer have suggested that the tumour is the source of hormone production. The aim of this study was to determine the frequency of hyperprolactinaemia in patients with colorectal cancer before, during, and after surgery, and also to determine whether prolactin is produced by these tumours.

METHODS

Serum prolactin concentrations were measured in 20 patients with colorectal cancer before, during, and after surgical resection of their tumours. Samples taken during surgery included peripheral venous blood and blood taken from the main veins draining the tumour. To determine whether the tumour was responsible for the production of prolactin in these patients, paraffin wax embedded sections of tumour specimens were subjected to immunohistochemistry and western blotting using a monoclonal antibody to prolactin.

RESULTS

Five patients (three women, two men) had preoperative prolactin concentrations above the normal reference range, although this increase was of clinical importance in only two. After surgical resection of their tumours, prolactin concentrations remained high in both patients. All 20 patients had greatly raised prolactin values at the time of surgery, irrespective of whether this was measured in peripheral blood or in blood taken from veins draining the tumour. All 20 colorectal cancer tissue samples, including those with raised preoperative and/or postoperative prolactin concentrations, were negative for prolactin staining. Frozen tissue was also available in four cases. The absence of prolactin gene expression in these four tumours was confirmed both by repeat immunohistochemistry and by western blotting. A further 50 colorectal cancer cases examined by immunohistochemistry alone were also unreactive for prolactin.

CONCLUSIONS

The results of this study suggest that serum prolactin concentrations may occasionally be raised in colorectal cancer patients, but that the tumour is not the source of hormone production.

Use of neuroendocrine hormones to promote reconstitution after bone marrow transplantation

A survey of the previous literature and the data shown here indicate that neuroendocrine hormones such as growth hormone and prolactin may be of potential clinical use after bone marrow transplantation (BMT) to promote hematopoietic and immune recovery. The amounts of hormones used in our model do not promote weight gain suggesting that their lymphohematopoietic actions were independent of their anabolic effects. While the hormones may not produce the same extent of immune/hematopoietic effects when compared to conventional hematopoietic and immune stimulating cytokines (i.e. IL-2 or G-CSF), their pleiotropic effects and limited toxicity after systemic administration makes them attractive to test in the post-BMT setting. However, more work needs to be performed to understand the mechanism(s) of their action, particularly with regard to T-cell function and development.