Activated natural killer cells and interleukin-2 promote granulocytic and megakaryocytic reconstitution after syngeneic bone marrow transplantation in mice

Purified populations of natural killer (NK) cells were obtained from mice with severe combined immune deficiency (SCID). SCID spleen cells were cultured and activated with recombinant human interleukin-2 (rhIL- 2) in vitro. The activated NK cells were then transferred with syngeneic BALB/c bone marrow cells (BMC) and rhIL-2 into lethally irradiated syngeneic recipients to determine their effect on long-term hematopoietic reconstitution. On analysis, the transfer of rhIL-2- activated NK cells along with BMC resulted in significant increases in splenic and BM hematopoietic progenitor cells when compared with those for mice not receiving NK cells. Histologic and flow cytometric analysis showed a marked increase in granulocytic and megakaryocytic lineage cells present in the spleens of the mice receiving activated NK cells. Analysis of the peripheral blood indicated that the transfer of activated NK cells with BMC also significantly improved platelet and total white blood cell counts, with increases in segmented neutrophils. Erythroid recovery was not affected. Finally, lethally irradiated mice receiving activated NK cells and rhIL-2 along with limiting numbers of syngeneic BMC showed a marked increase in survival rate. These results show that the use of populations enriched for activated NK cells after syngeneic BM transplantation (BMT) has a profound enhancing effect on engraftment primarily affecting megakaryocytic and granulocytic cell reconstitution. Therefore, the transfer of activated NK cells and rhIL- 2 may be of clinical use to promote hematopoietic reconstitution after BMT.     

Release of oxygen metabolites from chemoattractant-stimulated neutrophils is inhibited by resting platelets: role of extracellular adenosine and actin polymerization

The effect of human platelets on chemoattractant-induced generation of oxygen metabolites in neutrophils was investigated, using luminol- enhanced chemiluminescence (CL). Resting platelets inhibited the extracellular, but not the intracellular, production of oxygen radicals in formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe)-stimulated neutrophils. Maximal effect was obtained at the physiological neutrophil/platelet ratio of 1/50. Similar results were acquired by adding supernatants of platelets, indicating a role for a soluble factor. Removal of extracellular adenosine by adenosine deaminase (ADA), or blocking of adenosine-receptors by theophylline, antagonized the inhibitory effects of platelets (or the equivalent supernatant) on the neutrophil respiratory burst. In contrast, accumulation of adenosine by apyrase enhanced the inhibition. Exogenous adenosine mimicked the effects of platelets on the fMet-Leu-Phe-induced respiratory burst. To further assess the role of platelet-derived adenosine, the platelets were fixed with paraformaldehyde. We found that fixed platelets, as well as their supernatant, inhibited the fMet- Leu-Phe-induced CL-response to the same extent as viable cells. These effects were also reversed by ADA and theophylline, respectively. A prior removal of adenosine in the platelet suspension by ADA, followed by treatment with erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA) to inactivate ADA, did not reverse the inhibitory action of platelets on the fMet-Leu-Phe-induced CL-response in neutrophils. However, if adenosine receptors of neutrophil at the same time were blocked with theophyline, the inhibition was significantly reduced. Platelets markedly increased the generation of adenosine in a neutrophil suspension. The effect was antagonized by S-(4-Nitrobenzyl)-6- thioguanosine (NBTG), but unaffected by alpha, beta-methyl- eneadenosine5'diphosphate (AMP-CP), indicating that the platelet- dependent accumulation of adenosine is due to an increased release of endogenous adenosine from neutrophils and not to a degradation of extracellular AMP. In correlation, NBTG, but not AMP-CP, reversed the platelet-mediated inhibition of the fMet-Leu-Phe-induced CL-response in neutrophils. Consequently, these data suggest that a platelet-derived factor increases the release of endogenously formed adenosine from neutrophils, terminating the production of oxygen radicals. The inhibition of oxidase activity was also associated with a platelet- induced polymerization of actin in the margin of the neutrophils. Treatment of neutrophils with cytochalasin B reversed the effects of platelets, both on F-actin content and CL-response. In summary, resting platelets limit the release of oxygen radicals from chemoattractant- stimulated neutrophils, thus preventing excessive damage to host tissues in the vascular space. This effect is suggested to be associated with an increase generation of neutrophil-derived adenosine enhancing an autoregulatory inhibitory pathway, and a peripheral accumulation of actin filaments forming a barrier for extracellular release of reactive oxygen radicals.     

Effect of n-3 and n-6 fatty acids on proliferation and differentiation of promyelocytic leukemic HL-60 cells

Promyelocytic leukemic HL-60 cells were incubated with different fatty acids. Arachidonic acid (AA; 20:4, n-6) and eicosapentaenoic acid (EPA; 20:5, n-3) were the most potent inhibitors of proliferation in a dose- dependent way. Retinoic acid (RA) was used as a positive control. Inhibitors of cyclooxygenase and lipoxygenase or addition of antioxidants did not influence the effect of EPA or AA on cell proliferation. Increased capacity to generate superoxide anions after phorbol ester treatment and a reduced serglycin messenger RNA level in cells treated with AA or EPA indicated that these fatty acids induced differentiation in HL-60 cells similar to that induced by RA. However, down-regulation of the c-myc mRNA level, also typical for differentiation with RA in HL-60 cells, was not observed in cells incubated with AA or EPA. Flow cytometric analyses showed that in cultures incubated with AA or EPA, the proportion of cells in the G1 phase of the cell cycle increased. Similar effects were observed with RA. By flow cytometry and light scatter analyses it could be shown that AA made 8% of the cells apoptotic and 7% necrotic. The corresponding numbers were 21% and 10% for RA-treated cells, and 19% and 32% for EPA- treated cells. The present study shows that AA and EPA reduce the proliferation rate of HL-60 cells. This is mediated by mechanisms independent of eicosanoids or lipid peroxidation products and is due to effects both on apoptosis/necrosis and cell differentiation.     

Current status and future opportunities for controlling acromegaly

Growth-hormone (GH) secreting adenomas, including acromegaly, account for approximately one-sixth of all pituitary adenomas and are associated with mortality rates at least twice that of the general population. The ultimate goal of therapy for acromegaly is normalization of morbidity and mortality rates achieved through removal or reduction of the tumor mass and normalization of insulin-like growth factor I (IGF-I) levels. Previously published efficacy results of current treatment modalities (surgery, conventional radiation, and medical therapy with dopamine agonists and somatostatin analogs) are often difficult to compare because of the different criteria used to define cure (some of which are now considered inadequate). For each of these modalities, pooled data from a series of acromegaly studies were reviewed for rates of IGF-I normalization, a currently accepted definition of cure. The results showed overall cure rates of approximately 10% for bromocriptine, 34% for cabergoline, 36% for conventional radiation, 50–90% for surgery for microadenomas and less than 50% for macroadenomas, and 54–66% for octreotide. These cure rates based on IGF-I normalization are generally less than those reported for cure based solely on GH levels. Novel new therapies for acromegaly include the somatostatin analog, lanreotide, Gamma Knife radiosurgery, and pegvisomant, the first in its class of new GH receptor antagonists. Although it does not appear that Gamma Knife radiosurgery results in significantly higher cure rates or fewer complications, it does provide a notable improvement in delivery compared with conventional radiation. Early studies have reported IGF-I normalization in 48% of lanreotide-treated patients and up to 97% of pegvisomant-treated.     

Debilitating diarrhoea and weight loss due to colitis in two RA patients treated with leflunomide

Diarrhoea and weight loss are frequently reported adverse events in rheumatoid arthritis (RA) patients receiving the disease-modifying antirheumatic drug (DMARD) leflunomide. According to the available literature these side effects occur mostly during the first 6 months of treatment, are rather mild and rarely lead to treatment withdrawal. In this report, we describe the clinical, endoscopic and histologic findings in two RA patients with severe diarrhoea and important weight loss more than 12 months after starting treatment with leflunomide. In both cases the symptoms were caused by colitis, but one had ulcerative and the other microscopic colitis. Despite treatment with budesonide the complaints only improved after withdrawal of leflunomide, making a causal relationship between this drug and the pathogenesis of colitis probable. The heterogeneous histopathological findings in these two patients, however, do not allow us to draw any definitive conclusions about the mechanism by which leflunomide causes diarrhoea and weight loss in RA patients. We conclude that persistent diarrhoea or weight loss in patients taking leflunomide can be more serious than what is previously reported in the literature. In such cases leflunomide treatment should be stopped and an endoscopic examination of the colon is recommended. Given the long half-life of this drug a washout procedure with cholestyramine should be considered whenever the problem is severe or persistent.     

Hand function and performance of daily activities in systemic lupus erythematosus

OBJECTIVE: To investigate hand problems in patients with systemic lupus erythematosus (SLE) and to explore consequences on the ability to perform daily activities. METHODS: One hundred nine patients with SLE completed a questionnaire assessing hand problems in terms of deficits in body structures, e.g., joints, and body functions including pain, grip force, and other physiologic functions of the hand, the Health Assessment Questionnaire (HAQ), and the Simple hand test. Patients who stated problems in hand function answered questions about performance of daily activities and to what extent different deficits in body structures and body functions interfered. RESULTS: Seventy-three percent of patients experienced hand problems and 42% reported interference with performance of daily activities. Problems from body structures of the hand were distributed relatively evenly over joints and tendons/muscles. Reduced grip force and activity-induced pain were the most commonly reported problems in body functions. The most affected activity area was productivity, namely household tasks, work at home, work/study, and child care; least affected was self-care. Reduced grip force followed by fumbling and pain were the most frequently reported body functions to create difficulties in performing daily activities. When comparing patients with and without difficulties in performing daily activities, there were significant differences in problems from tendons/muscles, joints in the thumb, reduced force, stiffness, fumbling, numbness/tingling, and the HAQ. CONCLUSION: A majority of the study group had hand problems and almost half of the group experienced difficulties in performing daily activities due to SLE. The most affected activity area was productivity, where reduced grip force, fumbling, and pain were the most interfering body functions.