Calculation of whole blood CO2 content

Currently used methods for calculating whole blood CO2 content from calculated plasma content, measured blood pH, hemoglobin concentration ([Hb]), and O2 saturation yield materially different results. In this study the constants of the fundamental equations relating blood CO2 content to plasma content have been reevaluated. An iterative computer technique was used to empirically derive appropriate constants from data obtained from nine healthy male subjects at rest and at several exercise work loads. A calculation was derived that fitted the data well [difference 0.02 +/- 1.19 ml/100 (SD) ml, r = 0.98] blood CCO2 = plasma CCO2 (Formula: see text) where plasma CCO2 = 2.226.s.plasma PCO2.(1 + 10pH-pK'), CCO2 is CO2 content, SO2 is O2 saturation, s is the plasma CO2 solubility coefficient, and pK' is the apparent pK [s and pK' are from the equations of Kelman (Respir. Physiol. 3: 111-115, 1967)].     

Bio-synthesis of PGD2 and TXB2 by rabbit blood monocytes

A method for the preparation of a highly purified sample of rabbit blood monocytes is described. The metabolism of arachidonic acid (AA) in these cells was studied. Mononuclear cells were prepared by centrifugation on Ficoll-Paque gradients and the monocytes were obtained by further centrifugation and adherence onto plastic culture dishes. These procedures provided a preparation which contained 95% monocytes (non-specific esterase positive). Incubation of [1-14C]-AA with these cells produced four major metabolites which were separated by TLC; these corresponded to prostaglandin (PG) D2, thromboxane (TX) B2, 12-hydroxyheptadecatrienoic acid (HHT) and 12-/15-hydroxyeicosatetraenoic acid (HETE). A minor product which co-migrated with PGE2 was also detected but neither 6-keto-PGF1 alpha nor PGF2 alpha were detected. Also, there was no evidence of the formation of 5-lipoxygenase products (5-HETE and LTB4) by rabbit monocytes with or without calcium-ionophore A23187-stimulation. The production of PGD2, TXB2 and PGE2 was further confirmed by analyzing [3H]-AA metabolites using high-performance liquid chromatography (HPLC) with tritiated standards as references. The biosynthesis of these compounds from endogenous substrate in A23187-stimulated monocytes was confirmed by specific radioimmunoassays with or without prior HPLC separation. The synthesis of immunoreactive LTB4 and LTC4 by A23187-stimulated cells was also monitored and found to be relatively low. The synthesis of PGD2, TXB2 and PGE2 from both exogenous and endogenous substrate was suppressed by treatment of the monocytes with indomethacin (10(-6) M).     

Interleukin-2 activates human peripheral blood eosinophils

The effect of interleukin (IL)-2 on eosinophil survival and mediator release was investigated in vitro. Human peripheral blood eosinophils were isolated and purified from mildly atopic donors and cultured on albumin-coated wells with different concentrations of IL-2, interferon (IFN)-gamma, and granulocyte-macrophage colony stimulating factor (GM-CSF) and their viability was evaluated after 4 days in culture. Eosinophils were cultured with IL-2 (1000 u/ml), IFN-gamma (1000 u/ml), or GM-CSF (10 ng/ml) for 18 h, or with platelet activating factor (PAF) (10(-6) M) for 20 min, and the release of eosinophil peroxidase (EPO) and IL-6 was measured. Nedocromil sodium (10(-5) M) was added with each of the above cytokines to study the inhibitory effect of this drug on EPO release. A significant increase of EPO release was induced by IL-2, IFN-gamma, and GM-CSF after 18 h in culture. IL-2 as well as IFN-gamma induced a significant IL-6 release from eosinophils. Nedocromil sodium significantly inhibited EPO release from eosinophils induced by IL-2 or PAF. These results show that IL-2 can activate peripheral blood eosinophils to release granule mediators (EPO) and cytokines (IL-6). Taken together with the presence of IL-2 receptors on eosinophils, we conclude that IL-2 is an important mediator in allergic inflammation and a possible target for pharmacological modulation.     

Conversion of PGE2 to PGF2alpha by fetal sheep blood

In an attempt to explain the differences in the concentration of primary prostaglandins in the circulation of adult and fetal sheep, we have examined the ability of whole blood from adult and fetal sheep to reduce PGE2 to PGF2alpha in vitro. PGF2alpha was the principal radioactive product formed from 3H PGE2 by both adult and fetal blood. The enzyme initial reaction velocity was significantly higher (P = 0.02) per ml of fetal than adult blood. The optimum enzyme pH (7.0 - 7.5) was similar for both adult and fetal blood. The Km of the enzyme in fetal and adult blood were 3.59 x 10(-7) M and 5.02 x 10(-7) M respectively (P greater than 0.05). There was no detectable metabolism of PGF2alpha by either adult or fetal sheep blood. The results indicate that prostaglandin 9-ketoreductase is present in both adult and fetal sheep blood. Differences in the activity of this enzyme are unlikely to explain the higher concentrations of PGE reported in the plasma of fetal lambs.     

IL-2-activated cord blood mononuclear cells

BACKGROUND: [corrected] Recent findings in cord blood (CB) research indicate the potential clinical usefulness of IL-2-activated CB in eradication of minimal malignant residual disease after hematopoietic stem cell transplantation. This feasible approach to immunotherapy merits further pre-clinical investigations using human tumor models of hematologic malignancy. METHODS: The aim of our study was to compare the anti-tumor potential of CB mononuclear cells (MNC), matured in the presence of IL-2, to BM, and to determine phenotype and cytokine secretion in IL-2 CB MNC culture during the peak of their anti-leukemia cytotoxic activity. Phenotype change was analysed with flow cytometry, cytokine secretion with ELISA tests and cytotoxic activity with cytotoxicity assays. RESULTS: Following IL-2 maturation, the phenotype of CB MNC was remarkably changed. Lengthening IL-2 culture to 8 days significantly increased CD8+, CD16+ CD56+, CD56+ and CD56+ CD8+ populations. Interestingly, FACS analyzes revealed the occurrence of CD8+ CD56+ cells that were not present in non-stimulated CB. Cultures progressively produced higher levels of INF-gamma, TNF-alpha and GM-SCF. The IL-2-activated cells manifested potent lytic capabilities against both NK- and LAK-sensitive tumor cell targets. DISCUSSION: At the peak of cytotoxic activity during 8-day IL-2 CB MNC culture, we found increased numbers of various cytotoxic cells and increased secretion of cytokines that may contribute further to their potential therapeutic effect. The duration of CB IL-2 cultures may be crucial for successful application of CB in transplant situations to boost the CB GvL.