Red blood cells carry out T cell growth and survival bioactivities that are sensitive to cyclosporine A

Red blood cells (RBC) have emerged as a novel regulatory cell type endowed with bioactivities toward activated human T cells. Herein we show that the RBC bioactivities act on intracellular pathways initiated by T cell receptor (TCR)-dependent and -independent stimuli, including IL-2, IL-15, and the mixture of phorbol dibutyrate and ionomycin. The RBC bioactivities preserve the antioxidant status and are capable of rescuing activated T cells from cell death induced by serum deprivation. They are not mediated by glycosylphosphatidylinositol-linked receptors or sialic acids, and kinetic studies revealed that they hasten the entrance into the cell cycle. By using cyclosporine A (CsA) and rapamycin (Rapa) we show that the RBC bioactivities are calcineurin-dependent. Thus, treatment of T cells with CsA, but not Rapa, impaired RBC bioactivities, and preincubation of RBC with CsA completely abolished their bioactivities. We have demonstrated that RBC carry out bioactivities that are sensitive to CsA.     

Association between pregnancy-associated alpha2-glycoprotein (alpha2-PAG) and mixed leucocyte reaction determinants on the leucocyte surface.

alpha2-PAG is present on the surface on mononuclear blood leucocytes and can be demonstrated predominantly on B-lymphocytes and monocytes. Pretreatment of cells with antibody to alpha2-PAG leads to a marked reduction in Fc-rosette formation. Competitive blocking experiments with specific antisera reveal a particularly close association between alpha2-PAG and MLR (mixed leucocyte reaction) determinants on the cell surface. These findings suggest one mechanism whereby alpha2-PAG may modify cell-mediated immune responses.     

A method for the determination of free neuraminic acid split from red blood cell receptors by attached Newcastle disease virus during simultaneous elution and hemolysis

Summary Determination of free neuraminic acid in chicken red blood cell (RBC) hemolysate becomes possible after deproteinization of the hemolysate by ethanol-chloroform followed by removal of the solvents by evaporation. This procedure permits the determination of in situ neuraminidase activity of virons preadsorbed on RBC receptors when the virus elution and hemolysis proceed simultaneously.     

Detection of a minor stimulating product involved in secondary allogenic proliferation of human lymphocytes in vitro]

In a family with a shared parental haplotype studied in MLR I and II we report that: 1) A secondary proliferation can be induced without a primary positive MLR; 2) In these conditions a minor determinant activating secondary proliferation is detected; 3) No significant association of this product with the available makers (HLA-A, B, C, D, Ly-Li) of the HLA region has been found so far; its localisation within or outside the MHC is under investigation.     

Modification of mixed lymphocyte reactivity between DLA-identical dog sibs, after in vivo sensitization

Mixed lymphocyte reactions (MLR) with cells from DLA-identical dog sibs are nonresponsive either in primary or in secondary interactions after in vitro priming. However, lymphocytes from animals sensitized in vivo against DLA-identical sibs can show increased proliferative response to their immunizing donor. The kinetics of this reaction are similar to MLR across the DLA-barrier, although its intensity is less important. This proliferation may reflect minor histocompatibility antigenic differences.     

Demonstration of a soluble factor capable of inhibiting allogenic lymphocyte proliferation in man]

During the secondary mixed lymphocyte reaction (MLR), i.e. after the double in vitro allogenic sensitization between responding and stimulating cells bearing at least one HLA-DR incompatibility, suppressor cells are developed [1]. They are able to inhibit a primary MLR provided that the stimulating cells possess the same DR incompatibility as the immunizing cells. We report here that this inhibition is due to the production by these cells of a soluble suppressor factor which acts on responding cells provided that they share at least one gene product of the HLA-D region with the cells producing the factor. This a feedback process of auto-inhibition occurring after hyperimmunization. The action of this suppressor factor seems to be genetically restricted to an as yet unknown locus in linkage disequilibrium with HLA-DR.     

Alteration of erythrocyte (see article) -ATPase by replacement of cholesterol by desmosterol in the membrane.

Cholesterol of red blood cells (RBC) is readily exchanged by desmosterol and vice versa. The resulting alteration in the sterol composition influences the specific (Na+ plus K+)-ATPase activity. It is suggested that this effect is due to an altered membrane fluidity.     

Alloantigens directed by the SL-A region control the mixed lymphocyte reaction in swine]

Immunizations between a pig bearing a recombined SL-A haplotype and related animals revealed serological defined antigens under the MLR region control. These antigens seemed to be carried by all types of lymphocytes so far studied, but with large quantitative differences. The blood nonadherent on nylon fiber lymphocytes carried very few antigens and platelets none at all. The data are compatible with the assumption that these newly discovered antigens are equivalent to the mouse Ia antigens.     

Änderungen des Elektrolytgehaltes von Erythrozyten und Plasma bei nephrektomierten Ratten

Summary After two-stage nephrectomy in rats the potassium concentration in the red blood corpuscles (RBC) decreases from 10.6 ± 0.3 to 5.5 ± 0.3 mEq per 100 ml of RBC within 48 h. The decrease is accompanied by a much smaller increase in the plasma potassium concentration; the hyperkaliemia in nephrectomized rats is less pronounced than in nephrectomized dogs or anuric humans. Na⁺ in RBC increases by about 44% after nephrectomy; while there is only a very slight decrease of Na⁺ in plasma. Plasma chlorides drop from 10.92 ± 0.08 mEq/100 ml of plasma to 6.00 ± 0.81 mEq % within 48 h after nephrectomy. RBC chlorides tend to increase again after an initial drop from 5.22 ± 0.07 to 3.82 ± 0.90 mEq% within the first 8 h.     

The effect of ether, pentobarbitone sodium and fentanyl on blood gases, acid-base balance and hematological parameters in the rat

Blood gases, acid-base balance and hematological parameters (RBC, PCV and Hb) were measured in adult rats of both sexes. The use of ether and fentanyl had a very little effect on the blood gases and acid-base balance. The induction of pentobarbitone anesthesia, however, was followed by a significant increase in PCO2 and TCO2, while the pH value decreased.     

Determination by three technics of cellular immunology of the antigenic determinants of the Ly-Li system expressed on human B lymphocytes]

A clear correlation has been observed between the presence of the antigenic B cell system Ly-Li detected serologically, and 3 cellular immunology techniques: 1. MLR inhibition by anti-Li serum; 2. level of restimulation of anti-Ly-Li in vitro primed lymphocytes; 3. detection of HLA-D alleles by homozygous typing cells. These results suggest that the allelic products detected serologically may be identical to those detected by the first two techniques, namely MLR inhibition and in vitro primed lymphocyte typing, and possibly HLA-D typing using homozygous typing cells, although the correlation was found to be repeatedly less clear for the last technique.     

Components of biological,including seasonal,variation in hematological measurements and plasma fibrinogen concentrations in normal humans

This study has been carried out in order to examine the components of biologicalaand, in particular, seasonal variation in hematologic measurements in normal humans. Toward this end, 26 normal volunteers had monthly blood samplings during one calendar year for determination of number of red blood cells (RBC) and platelets, hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), MC Hb (MCH), MC Hb concentration (MCHC), RBC distribution width (RDW), mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (PCT), and plasma fibrinogen concentrations. The data were analyzed by means of spectral analyses of a group of time series or a single time series, and by means of repeated measures analyses of variance. Most of the hematologic variables show seasonal rhythms, such as annual rhythms or harmonics, which are expressed as a group phenomenon. An important part of the variance (>15%) in Ht, MCV, MCH, MCHC, RDW, number of platelets, MPV and plasma fibrinogen was explained by a yearly variation. The peak-trough differences (expressed as a percentage of the mean) in the yearly variations in number of RBC, Ht, MCV, MCH, MCHC and RDW were very low (all<8.5%). Number of platelets (14.4%) and plasma fibrinogen values (28%) showed a high-amplitude yearly variation. All hematological variables, except MCHC, show a high interindividual variability which exceeds by far the intraindividual variability.     

Mixed lymphocyte reaction in human monoclonal gammopathies

Summary Ten multiple myeloma (MM) and 5 monoclonal gammopathies of undertermined significance (MGUS) were studied. The mixed lymphocyte reaction (MLR) proliferative response was of the same order of magnitude in MM and in MGUS as in normal controls. Normal results were obtained when pathological lymphocytes were used as either responding or stimulating cells. The addition of monoclonal anti-Ia antibodies completely abrogates the proliferative response as in healthy individuals. These results suggest that the immunological mechanisms supposed to be important in MLR are functionally normal in MM and in MGUS, although both the B and T cell lineages are involved in monoclonal gammopathies.This work was supported by CNR-PPFF Controllo della crescita neoplastica No. 82.00387.96. We thank Regione Piemonte which purchasel most of the technical equipment.     

Mécanisme d'action du chloramphénicol dans l'inhibition de la production d'anticorps induite par de différents types d'antigènes

Summary Chloramphenicol (CAF) administered to rabbits during the whole period of immunization, is able to suppress almost completely the antibody response against horse serum albumin and globulins (HSA, HSG) andEscherichia coli: on the other hand, it does not inhibit antibody response to heterologous RBC. The possible mechanism of the inhibiting action of the CAF in antibody response to HSA, HSG andE. coli is discussed, and some hypotheses are put forward on the possible reasons for the different behaviour of CAF on the immune response induced by heterologous RBC.     

Shape change of blood platelets induced by myelin basic protein

Summary Myelin basic protein (MBP) isolated from bovine spinal cord caused a marked shape change reaction of human blood platelets which was not accompanied by the release reaction and not inhibited by methysergide and spiroperidol. Only those basic proteins, including MBP, which had previously shown to exert neuronal depolarisation also induced the shape change reaction. Therefore, these findings may extend the use of platelets as neuronal models.Acknowledgment. We thank Miss B. Gieux and Miss M. Handschin for skilful technical assistance.     

Changes in red blood cell choline and choline-bound lipids with oral lithium

The influence of oral lithium on the concentration of red blood cell choline (Ch), lecithin, glycerophosphorylcholine (GPCh) and phosphorylcholine (PCh) was studied. The concentration of RBC Ch was significantly elevated and the concentration of lecithin, GPCh and PCh significantly depressed in 16 patients on oral lithium compared to 9 age-matched controls. We conclude that lithium markedly depletes the red blood cell of choline containing compounds including lecithin. These changes may be responsible for both the therapeutic efficacy and the toxicity of lithium.     

Shape change of blood platelets induced by myelin basic protein.

Myelin basic protein (MBP) isolated from bovine spinal cord caused a marked shape change reaction of human blood platelets which was not accompanied by the release reaction and not inhibited by methysergide and spiroperidol. Only those basic proteins, including MBP, which had previously shown to exert neuronal depolarisation also induced the shape change reactions. Therefore, these findings may extend the use of platelets as neuronal models.     

Changes in red blood cell choline and choline-bound lipids with oral lithium

Summary The influence of oral lithium on the concentration of red blood cell choline (Ch), lecithin, glycerophosphorylcholine (GPCh) and phosphorylcholine (PCh) was studied. The concentration of RBC Ch was significantly elevated and the concentration of lecithin, GPCh and PCh significantly depressed in 16 patients on oral lithium compared to 9 age-matched controls. We conclude that lithium markedly depletes the red blood cell of choline containing compounds including lecithin. These changes may be responsible for both the therapeutic efficacy and the toxicity of lithium.     

RIAM (Rap1-interacting adaptor molecule) regulates complement-dependent phagocytosis

Phagocytosis mediated by the complement receptor CR3 (also known as integrin α_Mß₂ or Mac-1) is regulated by the recruitment of talin to the cytoplasmic tail of the ß₂ integrin subunit. Talin recruitment to this integrin is dependent on Rap1 activation. However, the mechanism by which Rap1 regulates this event and CR3-dependent phagocytosis remains largely unknown. In the present work, we examined the role of the Rap1 effector RIAM, a talin-binding protein, in the regulation of complement-mediated phagocytosis. Using the human myeloid cell lines HL-60 and THP-1, we determined that knockdown of RIAM impaired α_Mß₂ integrin affinity changes induced by stimuli fMLP and LPS. Phagocytosis of complement-opsonized RBC particles, but not of IgG-opsonized RBC particles, was impaired in RIAM knockdown cells. Rap1 activation via EPAC induced by 8-pCPT-2′-O-Me-cAMP resulted in an increase of complement-mediated phagocytosis that was abrogated by knockdown of RIAM in HL-60 and THP-1 cell lines and in macrophages derived from primary monocytes. Furthermore, recruitment of talin to ß₂ integrin during complement-mediated phagocytosis was reduced in RIAM knockdown cells. These results indicate that RIAM is a critical component of the phagocytosis machinery downstream of Rap1 and mediates its function by recruiting talin to the phagocytic complement receptors.     

The effect of ether,pentobarbitone sodium and fentanyl on blood gases,acid-base balance and hematological parameters in the rat

Summary Blood gases, acid-base balance and hematological parameters (RBC, PCV and Hb) were measured in adult rats of both sexes. The use of ether and fentanyl had a very little effect on the blood gases and acid-base balance. The induction of petobarbitone anesthesia, however, was followed by a significant increase in PCO₂ and TCO₂, while the pH value decreased.Acknowledgments. The author gratefully acknowledges the excellent technical assistance of I. Bolliger, J. Heller, S. Küng, B. Müller, B. Schmidt and U. Völkle.