Stimulation of cellular sphingomyelin import by the chemokine connective tissue-activating peptide III.

The selective import of phospholipids into cells could be mediated by proteins secreted from the cells into the extracellular compartment. We observed that the supernatants obtained from suspensions of thrombin-activated platelets stimulated the exchange of pyrene (py)-labeled sphingomyelin between lipid vesicles in vitro. The proteins with sphingomyelin transfer activity were purified and identified as the chemokine connective tissue-activating peptide III (CTAP-III) and platelet basic protein. Isolated CTAP-III stimulated the exchange of py-sphingomyelin between lipid vesicles but did not affect the translocations of py-labeled phosphatidylcholine and phosphatidylethanolamine. CTAP-III rapidly increased the transfer of py-sphingomyelin from low density lipoproteins into peripheral blood lymphocytes, other immune cells, and fibroblasts. In the presence of heparin, CTAP-III was unable to insert sphingomyelin into the peripheral blood lymphocytes. The activation energy of the py-sphingomyelin transfer suggested that the translocation proceeded entirely in a hydrophobic environment. [(3)H]Sphingomyelin transferred to the cells by CTAP-III was hydrolyzed to [(3)H]ceramide and [(3)H]sphingosine after activation with tumor necrosis factor alpha. The generation of the [(3)H]sphingolipid messengers was catalyzed by acid sphingomyelinase. Our results identify CTAP-III as the first mediator of the selective (endocytosis-independent) cellular import of sphingomyelin allowing the paracrine modulation of the sphingolipid signaling.

Serum IgG, IgM, and IgA reactivity to human papillomavirus types 11 and 6 virus-like particles in different gynecologic patient groups.

Serum samples from several groups of patients attending a gynecology clinic were analyzed by ELISA for specific antibodies recognizing surface epitopes on intact human papillomavirus (HPV) types 6 and 11 L1 virus-like particles (VLPs) that were synthesized in vitro. In these samples, positive IgG and IgM reactivities to HPV-11 L1 VLPs were, respectively, 12% and 6% for 87 controls, 46% and 67% for 79 condyloma patients, 30% and 64% for 72 cervical intraepithelial neoplasia patients, 16% and 19% for 63 pregnant women at time of delivery, and 5% and 0 in their 63 newborns. IgA reactivities were low and not significantly different. The prevalence of IgG-positivity in HPV-6/11 DNA-positive patients increased from 46% with HPV-11 L1 VLPs to 76% when the sera were additionally screened with HPV-6 L1 VLPs. These data show that HPV-6 and -11 L1 VLPs are effective antigens for serologic studies and they detect type-specific antibodies.

Clinical trial of natural human lymphocyte-derived interleukin 2 in cancer patients: effects on cytokine production and suppressor cell status.

Lymphocyte-derived, natural, glycosylated interleukin 2 (IL 2) may have different effects in vivo than the non-glycosylated recombinant IL 2 hitherto employed in clinical trials. To test this, 9 tumor patients were given 3-6 x 10(6) U/day natural IL 2 by continuous infusion for 5 days. Compared with previously published results obtained using recombinant IL 2, as far as similar tests were performed, no unexpected results were obtained with natural IL 2 in the present study. Plasma TNF-alpha levels increased considerably during therapy, IFN-gamma very slightly, whereas IL 2-stimulated secretion of either cytokine in vitro fluctuated greatly. CD16+ and CD25+ cells increased and CD45R+ cells decreased after treatment, consistent with significant lymphocyte activation in vivo. MHC-unrestricted cytotoxicity increased after treatment. The level of CD8+ cells was and remained within the normal range, although suppressive activity generated in mixed lymphocyte culture was deficient prior to therapy. Interestingly, this normalised after therapy. These results extend studies of immunological monitoring of patients receiving IL 2, based on the first trial using natural rather than recombinant IL 2.

Cytokine regulation of the balance between alloindifferent and allospecific suppressor induction in mixed lymphocyte cultures.

The effects of exogenous cytokines on the generation of alloindifferent, MHC-unrestricted suppressive activity early on in mixed lymphocyte culture interactions have been investigated. Interleukin 4 strongly blocked the generation of suppression, whereas IL-1, IL-2, and IL-6 enhanced it to some extent. Tumor necrosis factor-alpha, interferons-alpha and -gamma, granulocyte/macrophage colony-stimulating factor, granulocyte CSF, IL-3 and IL-5, and a number of combinations of these factors were without effect in this system. Insofar as the alloindifferent suppression studied here also inhibited the development of allospecific, MHC restricted suppressive activity later in MLC, reduction by IL-4 of its development may have relevance for the use of this cytokine to facilitate the induction of specific suppressor cell-mediated transplantation tolerance in vivo.