Prolactin increases the susceptibility of primary leukemia cells to NK and LAK effectors.

Our previous studies have shown that prolactin (PRL), a pituitary and lymphocyte hormone and a ligand of the cytokine/hemopoietin receptors (R) superfamily, acts synergistically with interleukin (IL)-2 on the development of lymphokine activated killer (LAK) cells and enhances the effects of GM-CSF and IL-3 on myeloid progenitors' proliferation and differentiation. More recently, we have demonstrated that GM-CSF and IL-3 increase the sensitivity of acute myeloid leukemic (AML) cells to LAK activity. Together, these findings have prompted us to study the role of PRL on the target arm of the LAK response. We show here that CD33+ blasts from AML patients express membrane PRL-R and that the PRL/PRL-R interaction is followed by increased susceptibility to natural killer (NK) (p < 0.02) and LAK (p < 0.001) cells. As predicted from the dimerization model of PRL-R and in agreement with previous reports, the response of AML blasts to PRL was bell-shaped with a trend peak at 25 ng/ml. Although enhanced lysis occurred at the target recognition level, it was not accompanied by changes in the MHC class I, cellular adhesion molecules, or myeloid differentiation antigens. Cell cycle recruitment and lysis increased concurrently in three cases studied, suggesting a modulatory action of PRL on the expression of putative cycle-related NK/LAK-target structures. Together, these data strengthen the role of PRL in the LAK response.

Independent and synergistic effect of interleukin-2 and prolactin on development of T- and NK-derived LAK effectors.

We have studied the effect of recombinant (r)-Prl on the in vitro-induced MHC-unrestricted cytotoxicity of NK and T cells. A 4-day treatment with r-Prl in serum-free medium enhanced the cytotoxicity of NK cells to the NK-susceptible cell lines K562 and U937, but did not induce de novo NK cytotoxicity in T lymphocytes. By contrast, development of cytotoxicity against the LAK-susceptible cell lines HL60, Jurkat, Daudi and Supt-1 occurred in both NK and T cells. The effect of r-Prl on NK cells was bi-phasic with peaks at 25 ng/ml (1.2 nM), the upper physiological level, and 200 ng/ml (9.6 nM). By contrast, LAK activation of T cells only occurred at the highest r-Prl concentration. In addition to its intrinsic stimulatory activity, r-Prl was also capable of modulating in a dose-dependent manner distinct stages of the IL2-driven LAK/T differentiation pathway. Physiological concentrations of r-Prl interacted with low doses r-IL2 to significantly enhance generation of NK- and T-LAK activities. By contrast, pathological concentrations had opposite effects on generation of optimal LAK response, depending on the kind of LAK progenitor. The T-derived LAK activity was reversibly inhibited at the effector level, while the mature NK-LAK cells were stimulated. These data confirm our previous findings of a co-operative effect of Prl and IL2 on NK cell proliferation and reinforce the view that the signals conveyed by the two factors may be functionally related.

Modulatory effect of prolactin on the resting and mitogen-induced activity of T, B, and NK lymphocytes.

Prolactin (PRL) has been shown to contribute to the development of lymphoid tissues and maintenance of physiological immune function. Here we show that the role of the hormone extends to the control of the effector phase of the immune response. In addition to triggering resting lymphocytes to cell division, the hormone can also control the magnitude of their response to polyclonal stimuli. Concentrations of PRL in the physiological range increased the [3H]thymidine, [3H]uridine, and [3H]leucine incorporation of unstimulated NK cells cultured in serum-free conditions. The same concentrations of the hormone increased the response of NK, T, and B cells to the mitogenic stimuli interleukin 2 (IL2), phytohemagglutinin (PHA), and staphylococcus aureus cowan, respectively, the effect being maximally evident in the presence of suboptimal concentrations of the mitogens. By contrast concentrations of PRL five- to tenfold the physiological levels inhibited the mitogenic response to IL2 and PHA. These data indicate a double-faceted regulatory role of this hormone in vivo.

Normal development of lymphokine activated killing (LAK) in peripheral blood lymphocytes from hyperprolactinemic patients.

The effect of prolactin on the interleukin 2 (IL2)-driven development of Lymphokine Activated Killing (LAK) by normal PBL and by PBL from hyperprolactinemic patients was investigated. Concentrations of PRL corresponding to the physiological serum levels of the hormone and to the Kd of the PRL receptors on NK cells (6-20 ng/ml, 0.3-1 nM) had no effect on the generation of LAK activity by normal PBL, whereas 100-200 ng/ml were slightly, although significantly, inhibitory. By contrast, PBL from 16 hyperprolactinemic patients developed levels of LAK activity comparable with those generated by PBL from age- and sex-matched normoprolactinemic donors.

Effect of human interleukin 3 on the susceptibility of fresh leukemia cells to interleukin-2-induced lymphokine activated killing activity.

Pretreatment of acute myeloblastic leukemia cells with the hemopoietic growth factor interleukin 3 (IL3) increased their susceptibility to lymphokine activated killing (LAK) but did not affect their constitutive resistance to native natural killer activity. In addition, IL3 treatment did not alter the LAK cell-mediated killing of CD34+ hemopoietic progenitors present in normal bone marrow. Increased 3H-thymidine uptake was generally observed after IL3 treatment. However, failure to proliferate in response to IL3, observed in some cases, did not prevent changes in LAK susceptibility. Enhanced lysis of IL3-treated leukemic cells was accompanied by a moderate increase of the effector-target binding. Increased LAK susceptibility was already observed at 18 h, while optimal cytolysis and expression of the cell adhesion molecule (CAM) LFA-3 (CD58) by IL3-treated AML cells were concomitantly observed at later culture times. In contrast, the CAM ICAM-1 (CD54) was not modulated by IL3, nor were significant changes in the expression of either CAMs observed in normal hemopoietic cells. Blocking experiments with the anti-CD58 monoclonal antibody demonstrated a variable neutralizing effect on the IL3-induced increase of LAK activity, depending on the leukemia cell studied. The effect described here, together with the known role of IL3 in normal hemopoiesis makes it a factor of potential therapeutic value for the treatment of leukemic patients.

Pharmaceutical design and development of a Sinemet controlled-release formulation.

Many different formulation techniques are available for designing controlled-release dosage forms. Five different erosion-controlled or diffusion-controlled delivery systems were evaluated to select the 1 most suitable for Sinemet CR. The system ultimately selected, containing carbidopa-levodopa 50-200 mg, is a monolithic matrix tablet designed to have both of its active components released by surface dissolution and erosion. This system was found to be the most effective following extensive in vitro testing, pharmacokinetic studies, and clinical trials. Sinemet CR releases both carbidopa and levodopa by a 1st-order release rate. Controlled-release dosage forms of levodopa with slower in vitro release rates have lower plasma levels.

Cefoxitin sodium: solution and solid-state chemical stability studies.

Studies were undertaken to provide the basic physicochemical information necessary for preparing a suitable parenteral formulation of cefoxitin sodium. Emphasis was placed on the physico-chemical properties of the compound in solution and in the solid state. Cefoxitin sodium is very soluble in water and exhibits apparent first-order decomposition in this medium at pH 3-9. Maximum stability in water is at pH 5-7. Under these pH conditions, cefoxitin sodium loses about 10% of its activity in 2 days at 25 degrees. Thermal decomposition rates for amorphous and crystalline cefoxitin sodium samples were determined. Amorphous cefoxitin sodium was considerably less stable than its corresponding crystalline form. Solid-state decomposition plots are biphasic, displaying initial rapid losses followed by a slower decay period. The extent of loss in the crystalline solid at the end of the more rapid initial phase can be correlated with the water content of the solid.