Haematological and biochemical blood reference values for Canary Island camels (Camelus dromedarius), an endangered dromedary species

The purpose of this research was to develop reference values for haematological and biochemical variables in the Canary camel breed (Camelus dromedarius). 114 clinically healthy dromedary camels were assessed. Age, sex, and pregnancy status was also recorded. The reference range for red blood cells (RBCs) was 8.45 - 13.65 X10⁶/µL, haemoglobin (HGB) was 10.61 - 15.29 g/dL, packed cell volume (PCV) was 19.93 - 32.51 %, and white blood cells (WBCs) 7.35 - 18.36 X10³/µL. A correlation was established between the haemoglobin concentration (HGB) (g/dl) and packed cell volume (PCV) obtaining a linear regression (HGB = 0.31 PCV + 4.67). Young animals had higher RBC and WBC values than adult animals. Additionally, blood urea nitrogen (BUN), phosphorus, calcium, albumin/globulin (A/G) ratio, alkaline phosphatase, cholesterol, and lipase were higher in young animals compared with adults. Female dromedary camels showed higher values for the three main variables: RBC, HGB and PCV, but no differences between sexes were detected in the biochemical variables results. The WBC count was higher in non-pregnant females than in pregnant animals. These results provide references values for the Canary camel breed and may contribute to the understanding of differences in 18 haematological and biochemical parameters in dromedary camels with a potential impact in health and welfare for this species.

The A' and F' pockets of human CD1b are both required for optimal presentation of lipid antigens to T cells

CD1 proteins are unique in their ability to present lipid Ags to T cells. Human CD1b shares significant amino acid homology with mouse CD1d1, which contains an unusual putative Ag-binding groove formed by two large hydrophobic pockets, A' and F'. We investigated the function of the amino acid residues that line the A' and F' pockets of CD1b by engineering 36 alanine-substitution mutants and analyzing their ability to present mycobacterial glycolipid Ags. Two lipid Ags presented by CD1b were studied, a naturally occurring glucose monomycolate (GMM) isolated from mycobacteria, which contains two long alkyl chains (C54-C62 and C22-C24) and synthetic GMM (sGMM), which includes two short alkyl chains (C18 and C14). We identified eight residues in both the A' and F' pockets that were involved in the presentation of both GMM and sGMM to T cells. Interestingly, four additional residues located in the distal portion of the A' pocket were required for the optimal presentation of GMM, but not sGMM. Conversely, nine residues located between the center of the groove and the F' pocket were necessary for the optimal presentation of sGMM, but not GMM. These data indicate that both the A' and F' pockets of human CD1b are required for the presentation of lipid Ags to T cells.

Molecular recognition of human CD1b antigen complexes: evidence for a common pattern of interaction with alpha beta TCRs

Ag-specific T cell recognition is mediated through direct interaction of clonotypic TCRs with complexes formed between Ag-presenting molecules and their bound ligands. Although characterized in substantial detail for class I and class II MHC encoded molecules, the molecular interactions responsible for TCR recognition of the CD1 lipid and glycolipid Ag-presenting molecules are not yet well understood. Using a panel of epitope-specific Abs and site-specific mutants of the CD1b molecule, we showed that TCR interactions occur on the membrane distal aspects of the CD1b molecule over the alpha1 and alpha2 domain helices. The location of residues on CD1b important for this interaction suggested that TCRs bind in a diagonal orientation relative to the longitudinal axes of the alpha helices. The data point to a model in which TCR interaction extends over the opening of the putative Ag-binding groove, making multiple direct contacts with both alpha helices and bound Ag. Although reminiscent of TCR interaction with MHC class I, our data also pointed to significant differences between the TCR interactions with CD1 and MHC encoded Ag-presenting molecules, indicating that Ag receptor binding must be modified to accommodate the unique molecular structure of the CD1b molecule and the unusual Ags it presents.

Inhibition of human NK cell-mediated killing by CD1 molecules

It is now well established that NK cells recognize classical and nonclassical MHC class I molecules and that such recognition typically results in the inhibition of target cell lysis. Given the known structural similarities between MHC class I and non-MHC-encoded CD1 molecules, we investigated the possibility that human CD1a, -b, and -c proteins might also function as specific target structures for NK cell receptors. Here we report that expression of CD1a, -b, or -c can partially inhibits target cell lysis by freshly isolated human NK cells and cultured NK lines. The inhibitory effects of CD1 molecules on NK cell could be shown upon expression of individual CD1 proteins in transfected NK-sensitive target cells, and these effects could be reversed by incubation of the target cells with mAbs specific for the expressed form of CD1. Inhibitory effects of CD1 expression on NK-mediated lysis could also be shown for cultured human dendritic cells, which represent a cell type that prominently expresses the various CD1 proteins in vivo. In addition, the bacterial glycolipid Ags known to be bound and presented by CD1 proteins could significantly augment the observed inhibitory effects on target cell lysis by NK cells.

CD1 expression in human atherosclerosis. A potential mechanism for T cell activation by foam cells

Atherosclerotic plaques are chronic inflammatory lesions composed of dysfunctional endothelium, smooth muscle cells, lipid-laden macrophages, and T lymphocytes. This study analyzed atherosclerotic tissue specimens for expression of CD1 molecules, a family of cell surface proteins that present lipid antigens to T cells, and examined the possibility that CD1+ lipid-laden macrophages might present antigen to T cells. Immunohistochemical studies using a panel of specific monoclonal antibodies demonstrated expression of each of the four previously characterized human CD1 proteins (CD1a, -b, -c, and -d) in atherosclerotic plaques. Expression of CD1 was not observed in normal arterial specimens and appeared to be restricted to the CD68+ lipid-laden foam cells of atherosclerotic lesions. CD1 molecules colocalized in areas of the arterial wall that also contained abundant T lymphocytes, suggesting potential interactions between CD1+ cells and plaque-infiltrating lymphocytes in situ. Using CD1-expressing foam cells derived from macrophages in vitro, we demonstrated the ability of such cells to present lipid antigens to CD1 restricted T cells. Given the abundant T cells, CD1+ macrophages, and lipid accumulation in atherosclerotic plaques, we propose a potential role for lipid antigen presentation by CD1 proteins in the generation of the inflammatory component of these lesions.

An antimicrobial activity of cytolytic T cells mediated by granulysin

Cytolytic T lymphocytes (CTLs) kill intracellular pathogens by a granule-dependent mechanism. Granulysin, a protein found in granules of CTLs, reduced the viability of a broad spectrum of pathogenic bacteria, fungi, and parasites in vitro. Granulysin directly killed extracellular Mycobacterium tuberculosis, altering the membrane integrity of the bacillus, and, in combination with perforin, decreased the viability of intracellular M. tuberculosis. The ability of CTLs to kill intracellular M. tuberculosis was dependent on the presence of granulysin in cytotoxic granules, defining a mechanism by which T cells directly contribute to immunity against intracellular pathogens.

CD1c restricts responses of mycobacteria-specific T cells. Evidence for antigen presentation by a second member of the human CD1 family

Previous studies suggest that CD1 is a family of Ag-presenting molecules distantly related to those encoded by the MHC. However, of the four known human CD1 proteins, only CD1b has been shown to restrict Ag-specific T cell responses. In this study, we have shown that a second member of the human CD1 family, CD1c, could also mediate Ag presentation to T cells. Three T cell lines recognizing mycobacterial Ags in a CD1c-restricted manner were isolated from normal donor blood. These T cells were MHC unrestricted, and their recognition of Ag was independent of the products of the transporter associated with Ag presentation-1/2 and DMA/B genes that are generally required for Ag presentation by MHC-encoded Ag-presenting molecules. Furthermore, unlike MHC-restricted responses to peptides, the CD1c-restricted T cell lines recognized protease-resistant mycobacterial lipid Ags. These T cell lines also showed significant cytotoxicity toward CD1c-expressing target cells even in the absence of mycobacterial Ags, which was shown by clonal analysis to be mediated by a subpopulation of T cells directly reactive to CD1c molecules. Our findings establish the ability of a second member of the CD1 family to restrict responses of Ag-specific T cells, and thus support the general hypothesis that the CD1 family comprises a third lineage of Ag-presenting molecules that presents a novel class of foreign and self Ags to MHC-unrestricted T cells.

CD1c restricts responses of mycobacteria-specific T cells. Evidence for antigen presentation by a second member of the human CD1 family

Previous studies suggest that CD1 is a family of Ag-presenting molecules distantly related to those encoded by the MHC. However, of the four known human CD1 proteins, only CD1b has been shown to restrict Ag-specific T cell responses. In this study, we have shown that a second member of the human CD1 family, CD1c, could also mediate Ag presentation to T cells. Three T cell lines recognizing mycobacterial Ags in a CD1c-restricted manner were isolated from normal donor blood. These T cells were MHC unrestricted, and their recognition of Ag was independent of the products of the transporter associated with Ag presentation-1/2 and DMA/B genes that are generally required for Ag presentation by MHC-encoded Ag-presenting molecules. Furthermore, unlike MHC-restricted responses to peptides, the CD1c-restricted T cell lines recognized protease-resistant mycobacterial lipid Ags. These T cell lines also showed significant cytotoxicity toward CD1c-expressing target cells even in the absence of mycobacterial Ags, which was shown by clonal analysis to be mediated by a subpopulation of T cells directly reactive to CD1c molecules. Our findings establish the ability of a second member of the CD1 family to restrict responses of Ag-specific T cells, and thus support the general hypothesis that the CD1 family comprises a third lineage of Ag-presenting molecules that presents a novel class of foreign and self Ags to MHC-unrestricted T cells.

Antigen presentation by CD1 and MHC-encoded class I-like molecules

Three known lineages of antigen-presenting molecules restrict T-cell responses to microbial antigens: MHC class I and MHC encoded class I like molecules present peptides derived from the proteolysis of intracellular pathogens, MHC class ii molecules present peptides derived from the proteolysis of extracellular pathogens and CD1 molecules present unique microbial lipids and glycolipids. Recent studies have indicated that CD1 molecules mediate a novel system of antigen presentation and that MHC-encoded class I-like molecules can present unique subsets of intracellularly derived peptides.

Expression of the human apolipoprotein E gene is regulated by multiple positive and negative elements

Apolipoprotein E (apoE), unlike the other major lipoproteins, is synthesized in a variety of tissues. We examined which regions of the human apoE gene contributed to its tissue-specific expression using HepG2 and HeLa cells as examples of expressing and nonexpressing tissues, respectively. Regions between -360 bp and -80 bp and within the first intron were shown to be necessary for full expression activity in HepG2 cells by a nuclease protection assay which demonstrated correct transcriptional initiation of the transfected constructions. To fine map the regulatory regions, we constructed a series of deletions fused to the reporter gene chloramphenicol acetyltransferase. We discovered eight regions which had a positive effect on expression and three regions that had a negative effect on expression, in both HepG2 and HeLa cells. In addition we found three regions which had a tissue-specific negative effect on expression in HeLa cells and one region with a tissue-specific positive effect in HepG2 cells. A DNase I protection assay revealed eight footprints within the proximal 5'-flanking sequence and the first intron. Seven of these footprints fell within closely defined regions with positive expression activity. Sequence analysis of these footprint elements revealed the presence of previously identified elements and two novel elements related to each other, identified here as B1 and B2. We also defined another repeated sequence, the A element; all three of the tissue-nonspecific negative regions contained this element or sequences with homology to it. In the context of a heterologous promotor, a synthetic oligonucleotide containing the B1 and B2 elements behaved like a classical enhancer, having a positive effect on expression, even when placed at a distance. This effect was neutralized by a different synthetic oligonucleotide containing an A element repeat.

[Neonatal convulsions of a familial character and with a benign prognosis. Nosological classification. Apropos of a new case]

A new familial observation (3 members affected) of neonatal seizures without C. N. S. nor methabolic disturbance and subsequent normal development is reported. Seven other observations have been published before. The characteristics of this syndrome are discussed.