ON THE RELATION OF PRODUCTS OF ACTIVATED LYMPHOCYTES TO CELL-MEDIATED CYTOLYSIS

Experiments have been designed to test the hypothesis that soluble mediator production and T-cell-mediated cytotoxicity are necessarily related phenomena, and that soluble mediators may be involved in the mechanism of cytolysis. To this end, agents known to inhibit T-cell-mediated lysis in vitro have been studied for their effects on the production of two lymphocyte-derived mediators, lymphotoxin (LT) and migration inhibitory factor (MIF). A clear dissociation between mediator production and cell-mediated cytolysis was found using inhibitors of protein synthesis. Pactamycin and emetine, in doses of 10–7 M to 10–6 M, suppressed production of MIF and LT with only slight effect on killing of mastocytoma cells by immune T cells. On the other hand colchicine and vinblastine inhibited T-cell-mediated cytolysis in a dose-related manner but had no significant effect on either MIF or LT production, A striking dichotomy was also observed after augmentation of intracellular cyclic 3'5' adenosine monophosphate (cAMP) levels with cholera enterotoxin. Increased cAMP levels were associated with abrogation of direct lytic activity, but were without significant effect on MIF or LT production in guinea pigs or mice. These findings indicate that mediator production and direct lymphocyte-mediated cytolysis can be experimentally dissociated and represent independent cell-mediated immune functions

Total and Fractionated Bilirubin during the First Week in the Neonatal Intensive Care Unit

Background. Fractionated bilirubin requires more blood (0.6 ml) than total bilirubin alone (0.2 ml). Our focus during the first week in the Neonatal Intensive Care Unit (NICU) is on prevention of Bilirubin Induced Neurologic Dysfunction and kernicterus, which do not require fractionation. We wanted to determine the benefit of knowing fractionated bilirubin in the first week. Methods. In this retrospective study, data were obtained from the first week for 1202 NICU inborn admissions. Results. Direct bilirubin was more than 2.0 mg/dl in only six infants (0.6%). Five had multisystem injury from hypoxic ischemic events. One also had congenital cytomegalovirus and another had a postoperative liver hematoma. Weekly multichem profiles would have detected these abnormalities. No specific therapy was initiated for any of these infants. Conclusions. Converting to total bilirubin alone would not alter treatment, but could reduce iatrogenic blood loss by 2.4 ml per infant

THE PRODUCTION OF VESICULAR STOMATITIS VIRUS BY ANTIGEN- OR MITOGEN-STIMULATED LYMPHOCYTES AND CONTINUOUS LYMPHOBLASTOID LINES

A variety of lymphoid cell populations were examined in terms of their ability to replicate vesicular stomatitis virus (VSV), a lytic, RNA-containing virus maturing at the cell surface. The number of cells capable of producing VSV was estimated in terms of infectious centers by the virus plaque assay (VPA), and morphologically by electron microscopy (EM). The lymphoid cells examined in this study included: (a) lymph node cells from delayed hypersensitive guinea pigs stimulated by specific antigen, (b) mouse spleen cells activated by selective bone marrow-derived (B) cell and thymus derived (T) cell mitogens, and (c) cells of human and murine continuous lymphoblastoid or lymphoma lines. In unstimulated cultures of guinea pig lymph node cells there is a background of approximately 1 in 1,000 cells which produces VSV; in purified protein derivative (PPD)-stimulated cultures the number of cells producing virus was 1.6% in the VPA and 1.9% by EM. These cells were large lymphocytes with some morphological features of transformed lymphocytes but were not typical blast cells. A few macrophages were associated with virus in both stimulated and control cultures. These observations indicate that (a) cells responsive to antigens, as detected by a marker virus, were lymphocytes; (b) cells other than lymphocytes (macrophages) were capable of replicating VSV even without antigenic stimulation; and (c) the correlation of results obtained by VPA and morphologic examination was usually quite good. Of the total number of mouse spleen cells stimulated with concanavalin (Con A), a T cell mitogen, 4.5 (EM)–5.7% (VPA) were associated with VSV. These were characteristic transformed lymphocytes, similar to phytohemagglutinin (PHA)-stimulated human lymphocytes. In contrast Escherichia coli lipopolysaccharide (LPS)-treated mouse spleen cultures contained lower numbers of virus plaque-forming cells. The majority of such cells associated with virus displayed extensive rough endoplasmic reticulum. Two cultured murine lymphomas containing lymphocytes with the θ surface marker (L5178Y and EL-4) showed a 15–100-fold higher incidence of virus-producing cells than leukemias (L1210 and C57Bl/6) which did not carry this marker. Similarly, the L2C guinea pig leukemia, a known B cell leukemia, yielded a low percent of virus plaque-forming cells (<2%). However, MOPC-104, a plasma cell tumor presumed to be of B cell origin, was found to be an efficient virus producer. There was a wide variation in the efficiency of VSV replication among human lymphoblastoid lines. One line, Wil-2, produced 80% infectious centers after 24 h of exposure to VSV, and all cells were associated with virus at the EM level. The relationship between the virus-producing cells and different lymphocyte subpopulations as well as the efficiency of the two assays for studying virus-producing lymphocytes is discussed

A Retrospective Descriptive Study of Stat TPN Orders in the Neonatal Intensive Care Unit

BACKGROUND: Total parenteral nutrition (TPN) is used in the Neonatal Intensive Care Unit (NICU) to meet metabolic demand and provide growth. To prevent harm from critical laboratory abnormalities, stat TPNs can be ordered urgently to change the content of infusing TPN. Each stat order breaks the daily cycle and often leads to additional stat orders. Limited supplies of ingredients brought focus on our liberal stat TPN policy and how to reduce the number of stat TPNs safely. The purpose of this project was to evaluate biochemical abnormalities associated with stat TPNs and identify leverage points to reduce stat TPNs in NICU patients. METHODS: Data from 1/1/10 to 6/30/10 were abstracted from Meditech, NeoData, and patient charts for NICU stat TPN orders. Demographics, laboratory results (sodium, potassium, calcium, and glucose), and key variables were gathered and critical laboratory values were identified. RESULTS: A total of 112 patients had evaluable orders for 255 stat TPNs. Mean gestation was 31 weeks (SD = 5) and birth weight was 1.744 kg (SD = 0.993). Seven (3%) were never infused. Twenty (12.6%) of first stat TPNs were from patients taking nothing by mouth. Eighty-eight of first stat TPNs had no critical labs (55% of initial stat TPNs). Of follow-up stat orders, 43% (38/89) followed unnecessary initial stat TPNs. Of the 55 abnormalities that generated the initial stat TPNs, 44 (80%) corrected. CONCLUSIONS: Fifty-two percent of stat TPNs could not be justified. For situations that were justified, 20% of laboratory abnormalities from initial stat TPNs were not corrected. These data provide an opportunity to reduce unnecessary costs and save limited resources