NILR-1, a novel immunoglobulin-like receptor expressed by neutrophilic granulocytes, is encoded by a leukocyte receptor gene complex on rat chromosome 1

Several receptors expressed by subsets of leukocytes and with sequence homology to the killer cell inhibitory receptors have recently been identified both in man and mouse. Here we describe a rat cDNA that encodes a novel receptor of this group, designated neutrophil immunoglobulin-like receptor-1 (NILR-1). The predicted 58.7-kDa mature NILR-1 protein is a type I integral membrane protein, with three C2-type immunoglobulin superfamily domains, a transmembrane region devoid of charged amino acids, and a cytoplasmic tail containing four immunoreceptor tyrosine-based inhibition motif-like regions. NILR-1 shows greatest sequence homology to the mouse paired immunoglobulin-like receptor-B and members of the human leukocyte immunoglobulin-like receptor/immunoglobulin-like transcript group of receptors. As shown by Northern blot analysis, NILR-1 was transcribed by neutrophilic granulocytes. Although weaker transcription was found with a macrophage cell line, no signal was detected with peritoneal macrophage or spleen RNA. Linkage analysis localized Nilr1 to chromosome 1, closely linked to a locus encoding a rat NKp46 orthologue. The two loci define a rat leukocyte receptor gene complex, in a region syntenic to human chromosome 19q13.4 and the proximal part of mouse chromosome 7, that harbors the human and mouse leukocyte receptor gene complexes.

Contact activation factors in plasma from women on estrogen replacement therapy after ovariohysterectomy

The plasma levels of factor XII, prekallikrein, factor XI, and high molecular weight kininogen were studied in women with bilateral oophorectomy and hysterectomy who received hormone replacement therapy with a 2 mg daily dose of estradiol valerate. Also plasminogen activator activity was investigated. The observations made provide support for the assumption that the low doses of estrogen used in hormone replacement therapy do not significantly affect the levels of contact activation or fibrinolytic factors in plasma. Plasma obtained from young, healthy women was used as a standard reference material. Significantly higher levels of factor XII and prekallikrein were registered in functional tests in the ectomized women than in the reference material, an increase not observed in the immunological assays. These observations are discussed in light of recently published data from our laboratory on an increase in the measured level of factor XII obtained upon the removal of IgG before assay. Also a marked increase in urokinase activity was registered in the ectomized women. The high levels of factor XII, prekallikrein, and urokinase, as compared with the reference material, seemed to be age dependent, being also observed in a group of naturally postmenopausal women.

Constant temperature monitoring: a study of temperature patterns in the postanesthesia care unit

Patients admitted to the PACU from the operating room exhibit fluctuations in core body temperature during the course of their stay in the PACU. Some patients present with normothermia and experience temperature decreases later in their stay. PACU policy does not dictate that temperatures be measured at a predetermined frequency in the absence of hypothermia; thus, it is possible that hypothermia may not be detected at its onset. The major purpose of this study was to describe the core body temperature patterns of postsurgical patients during the PACU stay. Secondary objectives were to (1) identify at which point in time patients become hypothermic and (2) describe length of stay in patients who develop hypothermia. Hypothermia was defined as a core tympanic temperature of less than 35.5 degrees C. A descriptive design was used using a convenience sample of 150 elective surgical patients over the age of 1 month who were normothermic on admission to the PACU. Data were analyzed using descriptive statistics. Concurrent tympanic and continuous axillary temperatures were monitored for comparison and trend monitoring. Temperatures showed clinically significant decreases into the hypothermic range (< 35.5 degrees C). Fifty-seven percent of the sample (n = 86) had temperatures that dropped after PACU admission and another 13% fell below 35.5 degrees C. Hypothermia occurred within the first 15 minutes of the PACU stay. The average length of stay for those that developed hypothermia was 1.83 hours. Monitoring temperatures more frequently will result in detecting hypothermia at its onset. Nurses may use the axillary device as a trend for continuous monitoring. Length of stay may be shortened if temperature management is embraced by the PACU nurse.

Identification of a human member of the Ly-49 multigene family

Three classes of multigene family-encoded receptors enable NK cells to discriminate between polymorphic MHC class I molecules: Ly-49 homodimers, CD94/NKG2 heterodimers and the killer cell inhibitory receptors (KIR). Of these, CD94/NKG2 has been characterized in both rodents and humans. In contrast, Ly-49 family members have hitherto been found only in rodents, and KIR molecules only in the human. In this report, we describe a human cDNA, termed Ly-49L, that constitutes the first human member of the Ly-49 multi-gene family. Compared with rodent Ly-49 molecules, the Ly-49L sequence contains a premature stop codon and predicts a truncated protein that lacks the distal part of a C-terminal lectin domain. Evidence is presented that the premature stop codon results from incomplete excision of the intron between the first two lectin domain exons. Splice variants predicting a full-size Ly-49L protein were not detected. As demonstrated by Northern blot analysis, Ly-49L was transcribed by IL-2-activated NK cells, but not by freshly isolated B or T cells. PCR screening of a 22-clone yeast artificial chromosome contig localized the LY49L locus to the human NK gene complex on chromosome 12p12-p13. Southern blot analysis of genomic DNA showed a simple pattern with a full-length Ly-49L probe at low stringency hybridization conditions, suggesting that Ly-49L may be the only human member of the Ly-49 multigene family.

Molecular characterization of rat NKR-P2, a lectin-like receptor expressed by NK cells and resting T cells

The gene for a rat NK lectin-like receptor (NKLLR), named NKR-P2, has been cloned and characterized. Sequence analysis shows that it represents the orthologue of human NKG2D and that the two molecules form a distinct NKLLR family, no more related to NKG2A/B, -C or -E than to other NKLLR families. Nkrp2 is a single-copy gene containing seven introns, mapping to the rat NK gene complex. Rat NKR-P2 differs from the human orthologue in that its cytoplasmic tail contains 13 additional amino acids, encoded by a separate exon. Splice variants lacking this exon were not detected in T cells or NK cells. NKR-P2 is strongly expressed by NK cells. In contrast to other NKLLR, it is also strongly expressed by resting thoracic duct CD4+ and CD8+ T cells, but not by thymocytes or other hemopoietic cells.

Two genes in the rat homologous to human NKG2

Two different lectin-like receptors for MHC class I molecules have so far been identified on natural killer (NK) cells, the Ly-49 homodimeric receptors in mice and the NKG2/CD94 heterodimeric receptors in humans. The recent identification of a rat CD94 orthologue implied that NK cell receptors equivalent to NKG2/CD94 also exist in rodents. Here we describe the cDNA cloning of two rat genes homologous to members of the human NKG2 multigene family. The deduced rat NKG2A protein contains a cytoplasmic immunoreceptor tyrosine-based inhibition motif (ITIM), whereas the cytoplasmic tail of rat NKG2C lacks ITIM. The genes map to the rat NK gene complex and are selectively expressed by NK cells. The expression is strain dependent, with high expression in DA and low in PVG NK cells, correlating with the expression of rat CD94. Ly-49 genes have previously been identified in the rat, and the existence of rat NKG2 genes in addition to a CD94 orthologue suggests that NK cell populations utilize different C-type lectin receptors for MHC class I molecules in parallel.

Molecular characterization of a gene in the rat homologous to human CD94

Three classes of major histocompatibility (MHC) class I binding receptors on natural killer (NK) cells have so far been described: CD94/NKG2 heterodimeric receptors and killer cell inhibitory receptors in the human, and Ly-49 homodimers in rodents. CD94, NKG2 and Ly-49 belong to the C-type lectin superfamily. As yet, CD94 and NKG2 molecules have not been detected in rodents or Ly-49 in humans. It has therefore been proposed that the two receptors represent functional equivalents in these species. The present study describes the cDNA cloning of a novel rat gene encoding a protein of 179 amino acids, 54.2% identical to human CD94. The single-copy Cd94 gene is localized to the rat NK gene complex (NKC), within 50 kb from Nkrp2, between the Nkrp1 and Ly49 gene clusters. By Northern blot analysis, we showed that rat CD94 is selectively expressed by NK cells and a small subset of T cells, similar to the human orthologue. This expression is strain dependent, with high expression in DA NK cells and low in PVG NK cells. Evidence is presented that this difference is not due to receptor repertoire shaping by MHC-encoded ligands, but is controlled by genetic elements residing within the NKC. The identification of a rat CD94 orthologue suggests that NK cell populations utilize two different C-type lectin receptors for MHC class I molecules in parallel.

Urokinase and non-urokinase fibrinolytic activity in protease-inhibitor-deprived plasma, assayed by a fibrin micro-plate method

In the classical fibrin-plate assay, fibrinolytic activity is determined by measuring the area of the lysis zone formed when sample is applied on a planar fibrin gel. However, this method is characterized by low capacity and uncertainty in the determination of the lysis zones. To overcome these limitations an assay modified for microtiter plates was developed. Fibrin clots, with a suitable dye incorporated, were formed in wells of standard high adsorbtion microtiter plates. Each plate contained a serial dilution of urokinase as standard. Citrated test plasmas were treated with acetone to remove inhibitors before applied to the wells. The lyzate formed after appropriate incubation was removed, and the remaining volume of fibrin photometrically determined after being completely dissolved by plasmin. The fibrinolytic activity was determined as the difference in absorption before and after lysis. This is an accurate and relatively simple method for the assessment of urokinase and non-urokinase fibrinolytic activity in plasma. It is further a sensitive and quantitative fibrinolytic micro-technique with a high capacity.

An autosomal dominant locus, Nka, mapping to the Ly-49 region of a rat natural killer (NK) gene complex, controls NK cell lysis of allogeneic lymphocytes

Natural Killer (NK) cells can recognize and kill MHC-incompatible normal bone marrow-derived cells. Presently characterized MHC-binding receptors on NK cells, including the Ly-49 family in the mouse, transmit inhibitory signals upon binding to cognate class I MHC ligands. Here we study in vivo NK-mediated lysis of normal allogeneic lymphocytes in crosses between alloreactivity-competent PVG rats and alloreactivity-deficient DA rats. NK cells from both strains are able to lyse standard tumor targets. We identify an autosomal dominant locus, Nka, that controls NK-mediated alloreactivity. Individuals carrying the dominant PVG allele in single dose were fully competent in eliminating allogeneic target cells, suggesting that Nka encodes or regulates a gene product inducing or activating alloreactivity. By linkage analysis and pulsed field gel electrophoresis, a natural killer gene complex (NKC) on rat chromosome 4 is described that contains the rat NKR-P1 and Ly-49 multigene families plus a rat NKG2D homologue. Nka maps within the NKC, together with the most telomeric Ly-49 family members, but separate from NKG2D and the NKR-P1 family. The Nka-encoded response, moreover, correlates with the expression of transcripts for Ly-49 receptors in NK cell populations, as Northern blot analysis demonstrated low expression of Ly-49 genes in DA NK cells, in contrast to high expression in alloreactivity-competent PVG, (DA X PVG)F1, and PVG.1AVI NK cells. The low Ly-49 expression in DA is not induced by MHC haplotype, as demonstrated by high expression of Ly-49 in the DA MHC-congenic PVG.1AVI strain. Finally, we have cloned and characterized the first four members of the rat Ly-49 gene family. Their cytoplasmic domains demonstrate substantial heterogeneity, consistent with the hypothesis that different Ly-49 family members may subserve different signaling functions.

Dendritic leucocytes pulsed with monoclonal antibody-hapten conjugates elicit vigorous primary humoral responses in vivo

Purified dendritic leucocytes (DL) were pulsed briefly in vitro with haptenated monoclonal antibodies (MoAb) to MHC class II and immediately injected i.v. into syngeneic recipients. Strong anti-hapten humoral responses were observed even though only a few picomoles of specific MoAb-hapten conjugates were injected with the DL. In contrast, DL pulsed with control conjugates, i.e. haptenated non-binding MoAbs, gave only weak responses. DL thus, can take up, process and present protein antigens even after brief exposure in vitro, and their immunogenicity is enhanced by pulsing with antigen conjugated to specific MoAbs. Furthermore, in the presence of fetal calf serum (FCS), but not normal rat serum, the control MoAb W6/32 (against human MHC class I) bound to DL. The vigorous primary humoral response achieved following this pulsing indicates that it is the binding and the corresponding increased uptake that enhances the immunogenicity of the DL.

Expression of CD43 epitopes on NK and T cells

CD43 epitope expression was studied with a panel of monoclonal antibodies (MoAbs) by immunohistochemistry on freeze sections of lymphoid tissues. The MoAb WEN3 stained most cells weakly in the T areas and scattered splenic red pulp cells strongly, whereas the other MoAbs strongly stained the majority of the cells in the T areas but gave variable staining patterns of cells in the non-T areas. Flow cytometry on CD4+ and CD8+ T cells (T4 and T8 cells), freshly isolated NK cells and LAK cells showed distinct staining profiles for each cell type, with epitope expression patterns of T8 cells lying between those of T4 cells and NK/LAK cells. T8 cells were split by one of the MoAbs, the NK cells, but not LAK cells, were split by two other MoAbs.

Contact factors in plasma from women on oral contraception--significance of factor XI for the measured activity of factor XII

The plasma levels of contact activation factors were measured in women using a low estrogen dose oral contraceptive (OC). Basic values for factor XII (FXII), factor XI (FXI), prekallikrein (PK), and high molecular weight kininogen (HK) were obtained in immunoassays by comparing with control plasma. The plasma levels of FXII and PK were significantly increased in OC plasma, to 147% and 146% respectively, whereas no significant increase could be registered for FXI (106%) or for HK (107%). Functional assays carried out with different peptide substrates (S-2222 for FXIIa, and S-2222, S-2302 and Bz-Pro-Phe-Arg-pNA for kallikrein) showed increases in OC plasma to about 150% for both proteases, in accordance with results obtained in radial immunodiffusion (RID). However, when FXIIa was measured with the high molecular weight substrate PK, no significant increase could be registered. Further experiments suggested this result to be due to the low level of FXI present in OC plasma, as compared to the levels of FXII and PK. Assays were carried out in mixtures of test plasma (OC or control plasma) and plasma deficient in FXI or FXII. The results obtained suggested that FXIa was present in some kind of association with part of FXIIa and part of kallikrein present. At low concentrations of FXI the functional activity of FXIIa was reduced, and the assay data indicated that an appropriate level of FXI was required to obtain maximum rate of hydrolysis of prekallikrein by FXIIa.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparing macrophages and dendritic leukocytes as antigen-presenting cells for humoral responses in vivo by antigen targeting

Immunotargeting is a novel technique whereby antigen is directed against antigen-presenting cells (APC) by conjugation to specific monoclonal antibodies (mAb). In this study we have employed the technique to investigate the efficiency of macrophages as APC compared with constitutively major histocompatibility complex (MHC) class II-positive cells, i.e. dendritic leukocytes and B cells, in vivo. We first studied the organ retention of the radiolabeled conjugates by gamma counting, and their distribution within the draining lymph nodes by autoradiography. We could confirm that the conjugates reached the cells at which they were aimed. We then measured primary and secondary humoral responses. The results confirmed previous findings that targeting with mAb against MHC class II, i.e. to dendritic leukocytes, strongly enhanced the primary humoral response. In contrast, anti-IgD conjugates, directed against B cells gave only weak primary responses. Although conjugates directed against macrophages were retained for a longer time than the other conjugates, the primary humoral response was virtually abolished. The secondary responses, however, were at least as strong as those obtained in animals primed with control conjugates, whereas animals primed with anti-MHC class II conjugates showed little if any amplification of the secondary response. The discrepancies between the various conjugates could not be ascribed to TH1 versus TH2 responses as IgG1, IgG2a, IgG2b and IgE titers all co-varied in single animals. A possible explanation for the observed results is that macrophages fail to induce cytokine production for terminal differentiation of B cells to plasma cells, whereas conversely, upon presentation by dendritic leukocytes most stimulated B cells mature to plasma cells, leaving less progeny for immunological memory.

Targeting antigens to antigen presenting cells

Antigen may be targeted to antigen presenting cells (APC) by conjugating the antigen to monoclonal antibodies directed against surface molecules on APC. By now several laboratories have shown that immunotargeting enhances humoral responses, depending upon the targeted ligand or cell type, with low doses of antigen and without the use of adjuvants. There is also preliminary evidence that the method may be used to bias immune responses in desired directions, possibly also to induce tolerance. In addition to its use as an experimental tool for exploring immune reactions the method could in the future also be clinically important, e.g. in vaccination. In this article we give a brief account on work so far published with this novel method and discuss possible mechanisms behind its immunopotentiating effects.

Antigen targetting with monoclonal antibodies as vectors--II. Further evidence that conjugation of antigen to specific monoclonal antibodies enhances uptake by antigen presenting cells

Immunization of rats with haptenized monoclonal antibodies (mAbs) against accessory cells enhances anti-hapten antibody responses. To see whether the mAb-conjugates really targetted the antigen (hapten) to the antigen presenting cells, we have investigated the lymph node distribution of locally injected radiolabelled conjugates. Compared with control conjugates, i.e. haptenized non-binding mAbs, a much larger proportion of the specific conjugates were retained in the draining lymph nodes. Whereas control conjugates were rapidly phagocytosed and degraded by macrophages, the specific conjugates were associated with the targetted accessory cells, which were radiolabelled for extended periods. Haptenated MRC OX6 (anti-MHC class II) gave strong labelling of interdigitating cells (IDC) in the paracortex with 70% of IDC still labelled by 4 days and 15% by 16 days following injection. By Western blots intact OX6 conjugates were still detected in the draining lymph node as long as 3 days after injections, whereas control conjugates were hardly detectable even by 24 h. The findings substantiate the idea that mAbs can be exploited for vectorial transport of antigens to accessory cells.

Allospecific recognition of hemic cells in vitro by natural killer cells from athymic rats: evidence that allodeterminants coded for by single major histocompatibility complex haplotypes are recognized

We have previously shown that large granular lymphocyte (LGL)-enriched cell populations have the capacity to spontaneously recognize and kill allogeneic small lymphocytes and bone marrow cells (BMC) in vitro in certain strain combinations of rats. Here, we have studied the alloreactivity of natural killer (NK) cells from PVG nude (RT1c) rats against a panel of major histocompatibility complex (MHC) incompatible hemic cells. Both lymphocytes and BMC from the AO (RT1u), DA (RT1a), BN (RT1n) as well as the MHC-congenic PVG-RT1u (RT1u) rat strains were efficiently killed in vitro, whereas cells from syngeneic PVG rats were spared. The structures recognized on lymphocytes and BMC were probably similar since the two cell populations inhibited each other in cross-competition experiments. A number of features aligned the alloreactive effector cells with NK cells and not T cells. (a) Only about 5% of the effector cells from nude spleens expressed the T cell antigens CD3, CD5 or T cell receptor (TcR) alpha/beta whereas greater than 50% of the cells expressed markers present on NK cells (CD2, CD8, OX52 and the rat NK cell-specific marker NKR-P1 recognized by the monoclonal antibody 3.2.3). (b) The alloreactive cells were granular since pretreatment of nude spleen cells with the lysosomotropic agent L-leucine methyl ester which eliminated LGL, simultaneously abolished the cytolysis of both allogeneic lymphocytes and YAC-1 tumor cells. (c) Nude spleen cells stimulated with human recombinant interleukin 2 for 1 week in vitro generated large granular proliferating cells which were CD3-, CD5-, TcR alpha/beta-, but greater than 95% 3.2.3+. These cells efficiently killed allogeneic hemic cells from the same rat strains as did freshly isolated effector cells. (d) The cytolysis of allogeneic hemic cells could effectively be inhibited with unlabelled NK-sensitive (YAC-1 and K-562), but not NK-resistant (Roser leukemia) tumor cells. Cross-competition studies showed that PVG nude NK cells discriminated between AO, BN and DA BMC, suggesting that different alloantigens were positively recognized by subsets of NK cells. The mode of inheritance of the allodeterminant specifically recognized on AO BMC was investigated in crosses and backcrosses between AO and BN or DA rats. A gene dosage effect was observed in that this determinant was expressed at a slightly reduced level in F1 hybrids.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaemia in elderly patients. Incidence and causes of low haemoglobin concentration in a city general practice

Haemoglobin concentration was determined in all patients (530) over 70 years of age in a general practice in Oslo during an eight month period. 72 had anaemia and were investigated further. Iron deficiency was found in 13 patients and was most often caused by gastrointestinal blood loss. Chronic diseases, particularly chronic infections and rheumatoid arthritis, were responsible for anaemia in 34 patients. Renal failure caused anaemia in 14 patients. In 10 patients we found no explanation for the anaemia. Nine patients with a previously undiscovered disease were found, six of whom could be offered some kind of treatment. We conclude that anaemia in elderly patients in general practice is often caused by chronic diseases. The main cause of iron deficiency is blood loss, and routine prescription of iron is not justified in this age group. The therapeutic benefit from routine measurement of haemoglobin concentration is small and the test should be used selectively.

The MRC OX-47 antigen is a member of the immunoglobulin superfamily with an unusual transmembrane sequence

The MRC OX-47 monoclonal antibody recognizes a membrane antigen present at low levels on many lymphocytes but whose expression is markedly increased on activation with mitogens. cDNA clones for the OX-47 antigen were isolated from an expression library and the protein sequence deduced. It contains a leader sequence giving a mature protein of 251 amino acids with a single putative transmembrane region, a cytoplasmic domain of 40 amino acids and an extracellular domain of 187 amino acids that contained two immunoglobulin-like domains. The putative transmembrane sequence includes a glutamic acid residue within the hydrophobic sequence. The presence of acidic residues within the hydrophobic sequence of transmembrane sequences usually indicates association with other polypeptides and this is predicted for the OX-47 antigen. A sequence of 37 amino acids that included all the transmembrane region was identical to that of the chicken HT7 antigen present on endothelium in brain and erythroblasts. The level of protein sequence identity in the Ig-like domains was lower but HT7 is almost certainly the chicken homologue of the rat OX-47 antigen. The ligand and function of the molecule are unknown. In addition to lymphoblasts the OX-47 antigen was localized on a variety of other cell types including various immature cells, endothelia and cells with excitable membranes.

Contact activation factors in plasma from pregnant women--increased level of an association between factor XII and kallikrein

The plasma levels of FXII, prekallikrein (PK), and high- and low molecular weight kininogens (HK and LK) were studied in pregnant women in the last trimester and in non-pregnant controls. FXIIa and plasma kallikrein were assayed in acetone-treated citrated plasma (CPLa) with the tetrapeptide S-2222 as substrate, using soybean trypsin inhibitor and corn inhibitor to exclude kallikrein and FXIIa respectively. No difference in PK-level could be registered for the two kinds of plasma, but the level of FXII had increased to about 150% in the pregnancy plasma. No difference in HK-level was observed, whereas the LK-level was significantly higher in pregnancy plasma, about 250% and 160% in rocket immunoassay and bioassay respectively. In fractions from gel filtration of plasma acetone-activated in the presence of benzamidine (BPLa), kallikrein was assayed as S-2302 amidase, HK and LK were measured in rocket immunoassay, and HK and FXII were studied in PAGE immunoblot experiments. In contrast to previous results obtained upon gel filtration of CPLa, not only kallikrein and HK, but in addition also FXII now appeared together in the same fractions and as two separate peaks. One peak eluting in early fractions (gel mol. wt. 300-400 KD), and one late eluting peak of proteins adsorbed to the gel material. The first peak was notably marked in pregnancy plasma. The results provide support for the assumption of an association in plasma between the three contact activation factors studied.