Recombinant Human Prolactin Improves Antitumor Effects of Murine Natural Killer Cells in vitro and in vivo

Abstract

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 µg, i.p.) was administered to BALB/c mice and severe combined immunodeficiency (SCID) mice 1 day before harvesting splenocytes for ⁵¹Cr release assay to examine the effects of rhPRL on NK cells of normal mice. rhPRL (10 µg, 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; 6,000 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.

Isolation of murine hepatic lymphocytes using mechanical dissection for phenotypic and functional analysis of NK1.1+cells

“…They exerted their versatile roles in the defense of pathogens like murine cytomegalovirus (MCMV) [21,22] . Several studies also reported that hepatic NK and NKT cell took part in the antimetastasis of tumor [23][24][25] . NK1.1 + cells were reported to involve in the pathogenesis of many diseases, like human immunodeficiency virus (HIV) infection and liver disease [26,27] .…”

Human Prolactin Promotes Human Secondary Immunoglobulin Response in Human/SCID Mouse Chimeras

“…The huPBL-SCID mouse has been demonstrated to be capable of mounting a human secondary Ig response to a variety of immunogens after immunization (31). Because rhPRL may improve the engraftment of human lymphocytes into lymphoid organs and promote general lymphocyte function, as reported previously (26,34), and the DT-specific proliferating response (Table 2) after in vivo treatment, we wanted to further observe if rhPRL acts as an adjuvant in DT immunization. It was noted that even without DT vaccine rechallenge, the baseline of DT-specific IgG was elevated after rhPRL treatment in huPBL-SCID mice ( Fig.…”

Expression of prolactin receptor and response to prolactin stimulation of human NK cell lines

“…Recombinant human prolactin was endotoxinfree and supplied as a gift by Dr. William J. Murphy, NCI-FCRDC, Frederick, MD, which has been used in their studies [22][23][24][25]. The IL-2-dependent NK cell line NK-92, established from a patient with rapidly progressive non-Hodgkin's lymophoma [26], was purchased from ATCC and maintained in a-MEM (Hyclone) medium containing100U/ml IL-2 and other necessary components as described [26].…”

“…PRL also increased the proliferating response and cytotoxicity of human, murine or rat NK cells to sensitive or insensitive tumor independently or synergistically with IL-2 in vitro [17][18][19][20]. We previously reported that PRL improved the hematopoiesis and lymphocyte development in syngeneic bone marrow transplantation [21][22][23][24], and exerted anti-tumor effects on tumor-bearing mice in vivo [25]. However, thus far there has been little evidence indicating that PRL can directly affect NK cell function through prolactin receptor on human NK cells.…”

“…IL-2, IL-15, PRL or combinations). The NK cells were admixed with 51 Cr-labeled K562 target cells for NK cytotoxicity at an effector (E) to target (T) ratio of 10:1, 5:1, 2.5:1 and 1.25:1 as previously described [25]. After standard 4 h incubation, the supernatant were harvested and analyzed on a gamma counter (model 5500; Beckman Instrument, Irvine, CA).…”