Search

Single nucleotide polymorphisms (SNPs) have been associated with an increased incidence of invasive aspergillosis (IA) after allogeneic stem cell transplantation (allo-SCT). We analyzed 41 patients with proven/probable IA after allo-SCT for an association of SNPs, within the TLR2, TLR4, TLR5, TLR9, and NOD2/CARD15 genes, with susceptibility to IA. The control group consisted of 130 patients who had allo-SCT but did not develop IA. While no association was found for donor SNPs and the recipients' risk of IA, analysis of recipient SNPs showed a significant association between the presence of recipient TLR5-Stop SNP (1174C> T) and the incidence of IA (P = 0.004). Multivariate analysis demonstrated that the recipient TLR5-Stop SNP appeared as an independent risk factor for IA after allo-SCT. Our study suggests that TLR5 is involved in host defense against Aspergillus fumigatus, and that the recipient TLR5-Stop SNP represents a risk factor for the development of IA after allo-SCT.

Nucleotide-binding oligomerization domain 2/caspase recruitment domain 15 (NOD2/CARD15) polymorphisms have been identified as risk factors of both Crohn's disease and graft-versus-host disease (GVHD) following allogeneic stem cell transplantation. However, the role of these receptors of innate immunity in the pathophysiology of gastrointestinal GVHD is still poorly defined. Immunohistological features of intestinal GVHD were analysed in gastrointestinal biopsies from 58 patients obtained at the time of first onset of intestinal symptoms. The observed changes were correlated with concomitant risk factors and the presence of polymorphisms within the pathogen recognition receptor gene NOD2/CARD15. Intestinal GVHD was associated with a stage-dependent decrease in CD4 T cell infiltrates and an increase in CD8 T cells in the lamina propria; CD8 infiltrates correlated with extent of apoptosis and consecutive epithelial proliferation. The presence of NOD2/CARD15 variants in the recipient was associated with a significant loss of CD4 T cells: in a semiquantitative analysis, the median CD4 score for patients with wild-type NOD2/CARD15 was 1.1 (range 3), but only 0.4 (range 2) for patients with variants (P = 0.002). This observation was independent from severity of GVHD in multivariate analyses and could not be explained by the loss of forkhead box P3(+) T cells. Our results suggest a loss of protective CD4 T cells in intestinal GVHD which is enhanced further by the presence of NOD2/CARD15 variants. Our study might help to identify more selective therapeutic strategies in the future.

Methylation of CpG islands is associated with transcriptional repression and, in cancer, leads to the abnormal silencing of tumor suppressor genes. We have developed a novel technique for detecting CpG-methylated DNA termed methyl-binding (MB)-PCR. This technique utilizes a recombinant protein with high affinity for CpG-methylated DNA that is coated onto the walls of a PCR vessel and selectively captures methylated DNA fragments from a mixture of genomic DNA. The retention and, hence, the degree of methylation of a specific DNA fragment (e.g. a CpG island promoter of a specific gene) is detected in the same tube by gene-specific PCR. MB-PCR does not require bisulfite treatment or methylation-sensitive restriction and provides a quick, simple and extremely sensitive technique allowing the detection of methylated DNA, in particular in tumor tissue or tumor cells from limited samples. Using this novel approach, we determined the methylation status of several established and candidate tumor suppressor genes and identified the ICSBP gene, encoding the myeloid and B-cell-specific transcription factor interferon consensus sequence-binding protein, as a target for aberrant hypermethylation in acute myeloid leukemia.

Objectives: This trial studied the efficacy and safety of itraconazole and fluconazole in the prevention of invasive fungal infections in neutropenic patients with haematological malignancies., Patients and Methods: An 8 week, open-label, randomized, parallel-group, multicentre trial comparing itraconazole oral solution (2.5 mg/kg twice daily; N=248) with fluconazole oral solution or capsules (400 mg daily; N=246) in 494 patients with anticipated profound neutropenia (i.e. neutrophil count expected to be <500 cells/mm3 for at least 10 days) from tertiary care centres., Results: Invasive fungal infections were reported for 4 out of 248 patients (1.6%) in the itraconazole group and 5 out of 246 patients (2.0%) in the fluconazole group. Invasive Aspergillus infections were proven for 2 out of 248 patients (0.8%) in the itraconazole group and 3 out of 246 patients (1.2%) in the fluconazole group. For both the ITT and profoundly neutropenic populations, no differences were detected between treatment groups in proven or suspected invasive fungal infections or other endpoints. The mortality rates owing to proven invasive fungal infections were 2 out of 248 patients (0.8%) for the itraconazole group and 3 out of 246 patients (1.2%) for the fluconazole group. There was also no difference between treatment groups in the number of patients who recovered from neutropenia or in the duration of neutropenia. More discontinuation of drug intake owing to nausea and more hypokalaemia occurred in the itraconazole group, other adverse events and the total number of adverse events were similar in both groups., Conclusions: In this study there were no differences in the efficacy and safety of itraconazole and fluconazole prophylaxis in neutropenic patients with haematological malignancies.

Background: Apoptosis of keratinocytes or intestinal epithelial cells is an important pathophysiological mechanism of organ damage during acute graft-versus-host disease., Objectives: To analyse in detail the mediators and their mutual interaction leading to keratinocyte apoptosis., Methods: Experiments were performed using a keratinocyte cell line (HaCaT) and human skin explant cultures., Results: Supernatants (SN) of major histocompatibility complex nonmatched mixed lymphocyte cultures (MLCs) induced apoptosis in HaCaT cells and also in keratinocytes from skin biopsies. Although both interferon (IFN)-gamma and Fas ligand (FasL) were detected in MLC-SN by enzyme-linked immunosorbent assay, the apoptosis-inducing capacity could be fully abrogated by neutralization of IFN-gamma, but not by neutralization of FasL. Recombinant (r) IFN-gamma induced HaCaT keratinocyte apoptosis in a dose- and time-dependent manner. Induction of HaCaT apoptosis by rFasL alone was induced only at higher doses than present in MLC-SN, but apoptosis was dramatically enhanced in the presence of rIFN-gamma. Further synergistic effects with IFN-gamma in the induction of apoptosis were also observed with agonistic antitumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor 2 antibody, soluble TRAIL and TNF-alpha. However, in contrast to FasL and TRAIL, TNF-alpha alone did not induce HaCaT apoptosis. Interleukin-1beta and lipopolysaccharide did not enhance the apoptosis-inducing effect of IFN-gamma. Beside its apoptosis-inducing capacity in HaCaT cells, rIFN-gamma also induced autocrine IFN-gamma production, and combined treatment with IFN-gamma and TNF-alpha induced autocrine TNF-alpha production. Neutralization of autocrine IFN-gamma protected HaCaT cells from apoptosis., Conclusions: Taken together, our data suggest a central role for IFN-gamma in HaCaT keratinocyte apoptosis but also show the importance of co-acting mediators such as TNF-alpha, TRAIL and FasL, which potentiate the effect of paracrine and autocrine IFN-gamma and TNF-alpha release.

The transmembrane form of tumor necrosis factor (mTNF), expressed on activated monocytes (MO) and macrophages (MPhi), is able to induce apoptosis in human endothelial cells (EC). Apoptosis is mediated by two distinct mechanisms: direct cell contact and a yet-unidentified soluble protein, death factor X. In addition, mTNF acts as a receptor that transduces a "reverse signal" into MO/MPhi when bound to the TNF receptor on EC. Reverse signaling by mTNF confers resistance to bacterial lipopolysaccharide (LPS). Stimulation of reverse signaling by mTNF blocks the ability of MO/MPhi to produce death factor X and proinflammatory cytokines. We have investigated which signaling pathways are used by mTNF acting as receptor. Reverse signaling triggers two independent pathways that can be distinguished by protein kinase C (PKC) inhibitors. The suppression of LPS-induced death factor X is dependent on PKC, whereas the suppression of LPS-mediated cytokine release is not. LPS and reverse signaling stimulate the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway. It is interesting that the activation of reverse signaling by mTNF renders MO/MPhi refractory to a subsequent activation of the MAPK/ERK pathway by LPS. Thus, reverse signaling achieves LPS resistance in monocytic cells through interference with key signal-transduction pathways.

Hematopoietic stem cell (HSC) homing from blood to bone marrow is a multistep process involving rolling, extravasation, migration, and finally adhesion in the correct microenvironment. With view to the hematopoietic recovery after clinical stem cell transplantation, we investigated the effect of stem cell factor (SCF) on the expression and the adhesive function of the alpha4beta1 and alpha5beta1 integrins very-late antigen (VLA)-4 and VLA-5 on peripheral blood-derived hematopoietic progenitor cells. After SCF stimulation, the expression of VLA-4 and VLA-5 on CD34+/c-kit+ cells obtained from healthy donors increased from 54% to 90% and from 3% to 82%, respectively. For patient-derived cells, the increase was 67% to 90% and 12% to 46%. The proportion of mononuclear cells adhering to the fibronectin fragment CH296 increased by stimulation with SCF from 14% to 23%. Accordingly, functional studies showed an approximate 30% increase of adherent long-term culture-initiating cell. The improvement of the homing abilities of SCF-stimulated HSC was confirmed by transplantation into sublethally irradiated nonobese diabetic-scid/scid mice. Six weeks after the transplantation, in eight of eight animals receiving human HSC with the addition of SCF, a profound multilineage hematopoietic engraftment was detected, whereas in the control group receiving only HSC, none of eight animals engrafted. Our data provide the first in vivo evidence that stimulation with cytokines improves the homing ability of transplanted human hematopoietic progenitor cells.

Macrophages in normal colonic mucosa show a specific and distinct phenotype with low expression of the typical monocyte/macrophage surface antigens CD14, CD16, and CD11b and T-cell costimulatory molecules. A method for the in vitro induction of a macrophage phenotype similar to this intestinal phenotype is presented. Multicellular spheroids (MCSs) of intestinal epithelial cell (IEC) and control cell lines were cocultured with elutriated monocytes. Surface antigen expression was analyzed by immunohistochemistry and flow cytometry. Interleukin (IL)-1beta mRNA was measured by quantitative PCR. Monocytes adhered and infiltrated the MCSs within 24 h. In the MCSs of all IEC lines, the typical monocyte/macrophage surface antigens CD14, CD16, CD11b, and CD11c, which are detectable after 24 h of coculture by immunohistochemistry and flow cytometry, were down-regulated after 7 days (e.g., for CD14 at 24 h, expression was 86% of CD33+ cells; at day 7, it was 11%). A clear decrease of lipopolysaccharide (LPS)-stimulated IL-1beta transcription in monocytes cocultured with IEC MCSs could be observed during the 7-day period. For the first time an intestine-like macrophage-phenotype could be induced in vitro. Interactions with IECs play an essential role during this differentiation, which is of functional relevance, e.g., for LPS-induced cytokine secretion.

Objective: Increased serum levels of a multitude of mediators like interleukins, tumor necrosis factor, elastase, adhesion molecules, and endotoxin have been described following cardiopulmonary bypass (CPB). The biological consequences of this complex response are unclear., Methods: Serum samples of nine patients scheduled for elective coronary artery bypass grafting were obtained preoperatively and 1, 6, and 12 h after weaning from CPB. Additional serum samples were obtained perioperatively from four patients undergoing major lung resection and from four healthy volunteers. The apoptosis-inducing activity of serum samples on endothelial cells was examined using a tissue culture assay system. Endothelial cells were derived from human umbilical cords and incubated for 48 h with serum samples in various dilutions during their second passage. The culture plates were fixed with methanol/acetone and stained with the DNA dye diamidinophenylindole. Apoptotic and normal cells were identified and counted using phase contrast and fluorescence microscopy., Results: The proportion of apoptotic endothelial cells was 5.6-fold higher in culture plates incubated with diluted (30%) serum samples obtained at 6 h after weaning from CPB when compared to plates incubated with preoperative samples (P=0.0077). A smaller effect occurred already at 1 h in some patients, whereas at 12 h after weaning from CPB no increased endothelial apoptosis was observed. No proapoptotic activity was found in preoperative as well as in control samples from patients undergoing lung resection or from healthy volunteers., Conclusions: Serum of patients after CPB exerts a strong apoptosis inducing activity on human endothelial cells. Apoptotic death of endothelial cells following CPB may be responsible for postoperative vascular and bypass dysfunction including phenomena like increased capillary permeability.

Adoptive transfer of host defense cells may be able to correct an otherwise defective generation of competent immune cells in patients with cancer. Ex vivo-grown cytotoxic macrophages (MAC) able to recognize and destroy tumor cells but not normal cells are effective in murine models of metastasizing tumors. After the development of large-scale technology to generate MAC in vitro from blood monocytes (MO), clinical trials in cancer patients have proven the feasibility and safety of infusing >3 x 10(9) autologous MO-derived MAC activated by interferon-gamma or lipopolysaccharide. Various modalities of adoptive immunotherapy with human MAC have been realized: routes of application used were intravenous, intraperitoneal, intrapleural, and through selective hepatic artery perfusion. In addition, MAC have been generated from MO collected after granulyte-macrophage colony-stimulating factor treatment in vivo. Biodistribution studies using 111indium-labeled cells have revealed localization of MAC to sites of bulk tumor growth on regional infusion as well as to liver metastases on systemic application. Malignant ascites disappeared in about 50% of patients after intraperitoneal treatment, yet no other evidence of therapeutic efficacy of MAC could be demonstrated. Further advances of adoptive transfer of MO-derived cells are developed with emphasis on the generation of antigen-presenting cells primed in vitro with tumor cells or specific peptides.

Glucocorticoids (GC) are potent anti-inflammatory and immunosuppressive agents that act on many cells of the body, including monocytes. Here we show that a 5-day course of high dose GC therapy differentially affected the CD14++ and the CD14+ CD16+ monocyte subpopulations in 10 patients treated for multiple sclerosis. While the classical (CD14++) monocytes exhibited a substantial increase from 495 +/- 132 to 755 +/- 337 cells/microl, the CD14+ CD16+ monocytes responded with a pronounced decrease from 36 +/- 15 to 2 +/- 3 cells/microl (P < 0.001). In 4/10 patients the CD14+ CD16+ monocytes fell below detection limits (<0.2 cells/microl). This observation was confirmed when the CD14+ CD16+ monocytes were identified by virtue of their low CD33 expression as these cells decreased as well. After discontinuation of GC therapy the CD14+ CD16+ monocytes reappeared and reached normal levels after 1 week. The profound depletion of CD14+ CD16+ monocytes by GC as described here is a novel effect of GC action in vivo and may contribute to GC-mediated immunosuppression. Determination of the number of this monocyte subset may also serve to monitor the effectiveness of GC therapy in patients requiring immunosuppressive treatment.

Macrophages play an important role in the intestinal mucosal immune system. However, they are a poorly defined cell population. We therefore determined their phenotype in normal colonic mucosa. Macrophages were isolated from colonic biopsies and surgical specimens by collagenase digestion. Colonic macrophages were positively sorted by anti-CD33 magnetic beads. Flow cytometric triple fluorescence analysis was applied to study CD14, CD16, CD33, CD44, CD11b, CD11c, CD64, HLA-DR, CD80, CD86 and CD3/CD19 expression. CD33 was evaluated as a positive marker for intestinal macrophages. CD33+ cells isolated from normal colonic mucosa showed co-expression of the established intracellular macrophage marker CD68 in FACS analysis. CD33+ cells were capable of phagocytosis. Isolation of this cell population by magnetic anti-CD33 beads and culture resulted in a 4.2-40-fold increase in IL-1beta and 4.5-44-fold increase in tumour necrosis factor-alpha (TNF-alpha) secretion compared with unsorted lamina propria mononuclear cells (LPMC). Of the CD33+ cells, 90.9 +/- 6.9% (mean +/- s.d.) were CD44+. However, macrophages from colonic mucosa showed only a low expression of CD14 (10.5 +/- 3.8%), CD16 (10.1 +/- 3.9%), HLA-DR (27.3 +/- 9.2%), CD11b (17.4 +/- 6.8%), CD11c (17.8 +/- 10.4%). Furthermore, expression of CD80 (9.2 +/- 4.2%) and CD86 (15.1 +/- 7.3%) was low, suggesting a low ability of normal intestinal macrophages to activate T cells and T cell-mediated immune responses. We conclude that CD33 is useful for the isolation and flow cytometric characterization of colonic macrophages. These cells exhibit a single phenotype in normal mucosa (CD33++, CD44++, CD14-, CD16-, CD11b-, CD11c-, HLA-DRlow, CD80-, CD86-) lacking lipopolysaccharide (LPS) receptor and costimulatory molecules.

Terminal maturation of blood monocytes (MO) in vitro and in vivo into macrophages (MAC) occurs as a result of interactions with various cell types. To characterize some of the cell-cell connections that may be important for MO differentiation we cocultured human MO with lymphocytes and/or with platelets. We found that intact platelets strongly promoted MO maturation under serum-free conditions as evident from the expression of differentiation-dependent antigens and morphology. To further characterize the differentiation-inducing component(s) we prepared membrane and cytosol fractions of platelets. Both fractions could induce MO maturation, comparable to intact platelets. Further centrifugation of the cytosolic fraction revealed that only the pellet of ultracentrifugation, e.g., membrane fragments, could induce MO differentiation. Digestion with either trypsin or neuraminidase could only partially inhibit this effect. The same was true for heat-treated fractions, indicating that this platelet-derived differentiation stimulus is not solely an intact protein. Next we prepared protein and lipid fractions of platelets. Treatment of MO with platelet proteins or platelet lipids clearly showed that only the lipid components were able to induce MO maturation. We propose components present in the lipid fraction of platelet membranes as possible inducers of MO maturation in vitro.

Maturation of cells of the mononuclear phagocyte lineage from bone marrow precursors to tissue macrophages (MAC) via circulating blood monocytes (MO) is a multistep process only partially understood. Similarly, MAC differentiation can be observed if MO are cultured in vitro. In an attempt to further characterize molecular changes occurring during this process we carried out differential screening of a MO-derived MAC cDNA library using MO and MAC cDNA. After subcloning and confirmation by a second round of screening, partial sequencing of 41 cDNA clones was performed. In 33 clones the sequences of 7 different previously identified cDNAs were found. The mRNA expression of two of the corresponding genes (apolipoprotein E, ferritin light chain) is already known to be up-regulated during MAC maturation. For one gene (cathepsin B), a specific up-regulation of mRNA expression could be shown corresponding to previous protein data. For four genes [human cartilage glycoprotein (HC-gp39), osteopontin, type IV collagenase, and tryptophanyl-tRNA synthetase] the specific expression in MAC versus MO was previously unknown but could be confirmed by the use of Northern blot analysis. Of these genes, HC-gp39 is especially interesting because it is only expressed during the late stages of MAC differentiation.

We were interested in the dependence of constitutive and stimulated cytokine secretion on the stage of macrophage (MAC) differentiation in vitro. Elutriation-purified blood MO were cultured up to 28 days and their secretory repertoire was analyzed under adherence conditions at various culture stages. For each of the cytokines tested, interleukin (IL)-1 beta, IL-6, tumor necrosis factor (TNF)-alpha, and macrophage colony-stimulating factor (M-CSF), a different pattern of regulation was observed. During the initial phase of maturation (up to day 7 in culture) within which the characteristics of normal MO to MAC transformation are achieved, M-CSF was the only cytokine to be secreted constitutively. From the LPS-dependent cytokines, IL-1 beta and IL-6 were downregulated whereas TNF-alpha levels increased severalfold. For the release of IL-1 beta, IL-6, and TNF-alpha a synergistic effect of interferon-gamma (IFN-g) and lipopolysaccharide (LPS) was observed. M-CSF release increased until day 7 in culture with LPS being stimulatory for this particular cytokine only during the first days of differentiation. Upon further cultivation of MAC up to 28 days, LPS-induced IL-1 beta levels remained very low, but IL-6 levels increased again reaching that of blood MO, and TNF-alpha continued to rise reaching levels up to 30-fold higher than in blood MO. M-CSF secretion stayed high with LPS even suppressing constitutive secretion. Long-term cultured MAC started to release IL-6 and TNF-alpha also in the absence of a stimulus and, furthermore, became responsive to IFN-g alone. Our data show that the release of each cytokine investigated is differently regulated during maturation. These results document the functional plasticity of human MAC and emphasize the impact that MO to MAC differentiation may have in vivo.

Functional competence as well as phenotype heterogeneity of macrophages depend on the completion of their maturation pathway. Differentiation of committed myeloid progenitor cells is induced by colony-stimulating factors (CSF), but no consistent data exist on which factor(s) induce the terminal maturation from the circulating blood monocyte to the mature macrophage. In vitro, monocyte to macrophage transformation occurs in the presence of serum and can be followed by the expression of the maturation-associated antigens gp65-MAX.1, gp68-MAX.3, and CD51. We describe that the differentiation-inducing activity in serum cannot be replaced by any of the known and available purified recombinant cytokines. In the absence of serum monocytes die in suspension cultures while surviving as non-differentiating cells when cultured adherent to plastic. In serum-free suspension cultures survival can be significantly improved by the addition of recombinant human macrophage (rhM)-CSF whereas other cytokines do not. At any stage of serum-free adherent culture, monocyte to macrophage differentiation can be induced rapidly by the addition of serum, whereas cytokines (rhM-CSF, recombinant human granulocyte macrophage [rhGM]-CSF, recombinant human granulocyte [rhG]-CSF, recombinant human interleukin [rhIL]-1, rhIL-3, rhIL-4, rhIL-6, tumor necrosis factor [TNF]-alpha, interferon [IFN]-alpha, IFN-gamma) alone or in combination are not effective. Serum-induced maturation, however, was suppressed in the presence of neutralizing anti-M-CSF antibodies. In addition to phenotype analysis, the secretory repertoire of rhM-CSF cultured monocytes was analyzed in comparison to serum cultured monocytes which further characterized them to be immature cells, i.e., low release of maturation-associated products such as alpha-2-macroglobulin, neopterin, fibronectin, and TNF-alpha, but high IL-6 secretion, an attribute of blood monocytes. We conclude that for monocyte survival in vitro the presence of endogenous M-CSF and possibly other autocrine factors elicited by cell adherence are required for the induction of macrophage maturation; however, yet undefined additional factor(s) are necessary. They are present in serum and may act in conjunction with M-CSF but are distinct from all known cytokines. Our in vitro system may be useful in the screening and discovery of these serum factor(s).

Cells of the mononuclear phagocyte system arise from circulating blood monocytes. Upon emigration from the vasculature, monocytes differentiate into macrophages, a process that monocytes similarly undergo in vitro. We have established primary cultures from elutriated or adherence-purified blood monocytes and analyzed the antigenic modulation during monocyte to macrophage transformation, which could be followed by the expression of specific antigens and which required as yet unknown inducer signals present in the serum. It is shown that in the absence of serum monocytes only survive in vitro when cultured adherent to plastic but rapidly die in suspension culture. Starting at 0.5%, serum induced maturation dose-dependently, with the optimal concentration being 2 to 5%. Of those antigens not present on monocyte, the low-affinity Fc receptor (CD16), the alpha-chain of the vitronectin receptor (CD51), gp65-MAX.1, and gp68-MAX.3 were expressed only upon serum-induced macrophage differentiation, whereas the transferrin receptor (CD71), MAX.26, and to some degree also gp65-MAX.11 appeared to be independent of maturation and were also found on primary cultures of adherent monocytes under serum-free conditions. In addition, the rapid induction of HLA class II antigens (within 24 hr) was similar with and without serum, as was the continued high-density expression in long-term culture. The monocyte-specific CD14 antigen was down-regulated in the absence of serum but kept its level of expression on differentiated macrophages. In comparison, alveolar and peritoneal macrophages, respectively, differed in their antigenic phenotype: Alveolar macrophages expressed high HLA class II antigens but low CD14, whereas for peritoneal macrophages the opposite was found. Both interferon-gamma and -alpha suppressed macrophage maturation in vitro but had contrary effects on HLA class II and CD16 expression: Interferon-gamma up-regulated the two types of antigens, which, in contrast, were down-regulated by interferon-alpha.

Sera collected from 1 tumor patient after a 12-hour infusion of 30-50 mg alkyl lysophospholipids (ALP)/kg induced a progressive destruction of human leukemia cells (HL60) in vitro. This cytotoxic serum activity correlated with the dose of ALP administered and was inhibited by the addition of a metabolizable lysophospholipid analogue. Human bone marrow cells and concanavalin A-stimulated lymphoblasts were affected to a much lesser degree, whereas cells of the erythroleukemia line K562 appeared to be relatively resistant. When cells were cultured in postinfusion sera, the cytotoxicity of ALP in vitro was enhanced as much as fifteenfold when compared with the cytotoxicity of ALP when the cells were cultured in normal sera. No change in either relative or absolute distribution of phospholipids in postinfusion sera could be detected.

Human alveolar macrophages as well as macrophages derived from Teflon culture of blood-borne monocytes were incubated with synthetic analogues of 2-lysophosphatidylcholine and then tested for their cytotoxic capacity against an allogeneic lymphoma cell line. Metabolic, rather stable analogues enhanced macrophage cytotoxicity significantly. This phenomenon was shown both in a growth-inhibition assay as well as in the 51Cr release assay. Macrophage activation was dose- and time-dependent and was potentiated at temperatures above 37 degrees C. Incubation of the macrophages with the active compounds induced characteristic changes in cell morphology as revealed by scanning electron microscopy.

Alkyl lysophospholipids (ALP) are synthetic analogs of the naturally occurring 2-lysophosphatidylcholine. The effect of ALP on the proliferation of 22 different gynecologic malignant tumors in humans was studied in vitro. ALP caused progressive death of tumor cells over 24-96 hours. In addition, tumor specimens from the tested human tumors were xenotransplanted into NMRI nude mice. ALP induced a highly significant retardation of the in vivo growing human tumors. Neither oral nor iv administration of these compounds caused any recognizable side effects.