[Demonstration of cell death process by apoptosis in cat lymphocytes infected by FIV (feline immunodeficiency virus)]

Feline immunodeficiency virus (FIV), the causative agent of feline AIDS, induces a disease syndrome in cats characterized by a decreased lymphocyte-proliferative response to mitogens at all stages of infection and selective depletion of CD4 lymphocyte subsets. In this work, we report that peripheral blood lymphocytes isolated from FIV-infected cats undergo a spontaneous death, in vitro, according to a programmed cell death (PCD) or apoptosis. This phenomenon has also been seen in peripheral blood lymphocytes from HIV-infected humans and SIV-infected macaques. Four different techniques were used to document PCD in FIV-infected cats. DNA gel electrophoresis has shown a DNA fragmentation pattern with DNA fragments displaying sizes corresponding to multiples of oligonucleosomes DNA length unit (180 bp). Transmission electron microscopy revealed condensation of both nuclear chromatin and cytoplasm. An increase in the percentage of fragmented DNA was demonstrated by Burton's technique. In addition, flow cytometric analysis detected a cell population with condensed chromatin. The spontaneous PCD in FIV-infected cats could not be inhibited by RNA synthesis inhibitors or protein synthesis inhibitors. Our results could have implications for understanding the pathogenesis of FIV-infection and establishing specific strategies against apoptosis in cats and humans.

Monitoring of early events of experimental woodchuck hepatitis infection: studies of peripheral blood mononuclear cells by cytofluorometry and PCR

The peripheral blood mononuclear cells (PBMC) of woodchucks experimentally infected by woodchuck hepatitis virus (WHV) were examined simultaneously for the presence of membrane associated WHV antigens by cytofluorometry, and for WHV DNA and RNA sequences by the polymerase chain reaction (PCR). Four woodchucks were inoculated: two with a well-defined infectious inoculum and two with an inoculum obtained from an animal at the late incubation phase, which was positive for WHV DNA by PCR but still devoid of WHV markers. Infection was demonstrated in all four inoculated woodchucks by the appearance at different times of WHV DNA and WHV antigens in both leucocytes and serum. WHV DNA was first detected by PCR either in the serum (two cases) or in leucocytes (two cases). The mean percentage of cells positive for membrane associated WHsAg or WHcAg detected by cytofluorometry were 37% +/- 25 and 17% +/- 15 respectively. After 8 weeks, all inoculated animals were WHsAg positive in serum. These data suggest that PBMC are involved in the early events of hepadnavirus infection. They also show that sera which are positive by PCR for WHV DNA may transmit viral infection even while still seronegative for WHV markers and for WHV DNA by dot blot.

Canine monocytes express a receptor specific for murine Fc gamma 2a and Fc gamma 3 immunoglobulins

Murine monoclonal antibodies (mAb) of IgM and IgG subclasses that do not bind to canine cells have been used to detect the expression of Fc receptors on canine peripheral blood mononuclear cells and the cell line MAXEY-DH82. Murine Ig of IgG2a and IgG3 isotypes bound specifically to canine peripheral blood monocytes and to MAXEY-DH82, whereas Ig of IgG1, IgG2b, and IgM did not. No other cell types, including resting and activated peripheral blood lymphocytes, expressed this canine Fc receptor (cFcR) specific for murine IgG2a and IgG3. MAXEY-DH82 was used to characterize this Fc gamma 2a/gamma 3 receptor. Binding of murine IgG2a and IgG3 is trypsin sensitive and partially suppressed by phosphatidyl inositol-phospholipase C (PI-PLC) treatment, indicating that this cFc gamma 2a/gamma 3 receptor is a lipid-anchored protein. Preincubation of MAXEY-DH82 with canine sera or canine IgG prevented the binding of murine gamma 2a/gamma 3 Ig, demonstrating that this receptor is a cFc receptor for canine IgG. The cFc gamma R expressed on canine monocytes and on MAXEY-DH82 is probably the analog of the murine and human Fc gamma RI. The specific expression of this analog by canine cells could be used in identifying and purifying canine monocytes.

Canine systemic lupus erythematosus. II: Antinuclear antibodies

The frequency and the specificities of antinuclear antibodies (ANAb) were studied in dogs with systemic lupus erythematosus (SLE) and compared to those found in normal dogs and in dogs with various infectious diseases. Whole ANAb were detected by immunofluorescence. Anti-double-stranded DNA Ab were found in only 2% of SLE dogs, whereas anti-single-stranded DNA Ab were present in 21.4% of SLE dogs and in 26.8% of dogs with infectious disease. Antihistone Ab were frequently observed in SLE dogs (71%) and are essentially directed against trypsin-resistant epitopes of H3, H4 and H2A. The Western blots of nuclear extracts of HeLa cells were recognized mainly by type 1 Ab (30%, reacting with bands of 43, 36, 35, 34, 30 and 27 kDa) and by anti-Sm Ab (12%) associated with anti-RNP Ab. Anti-SSA and anti-SSB Ab were rare.

Modification of human long-term bone marrow cultures: establishment of a functional stromal microenvironment devoid of myeloid progenitors

Differences in the plastic adhesive properties of bone marrow (BM) cells were used to initiate modified stromal layers (MSL) from long-term cultures by removing non-adherent cells shortly (4 to 18 hours) after initial seeding. Following this early modification, adherent cells generated a confluent layer after 21 days of culture. Cellular characteristics of volume and spontaneous fluorescence determined by flow cytometry showed that the MSL included 82% fibroblastic stromal cells, 8% macrophages and 10% myelomonocytic cells. Furthermore, clonogenic assays revealed that the MSL were devoid of hematopoietic progenitor cells. MSL were found to sustain long-term myelopoiesis for at least 7 weeks from exogenously added hematopoietic progenitors isolated from bone marrow (CD34+ cells), thereby demonstrating their functionality. The present experimental model appears of interest for the study of interactions between defined populations of hematopoietic cells and cells of the adherent layer. Of importance, our present modifications of human long-term bone marrow culture are technically simple and do not involve manipulation of the stromal cells.

Canine systemic lupus erythematosus. I: A study of 75 cases

We studied 75 cases of canine systemic lupus erythematosus (SLE) presenting with at least four criteria of the American Rheumatism Association (ARA), including antinuclear antibodies (ANAb). This disease mainly affects male German shepherds of an average age of 5 years. The most common clinical signs are polyarthritis (91% of cases), and renal (65%) and cutaneo-mucous disorders (60%). Hemolytic anemia is rare (13%). ANAb are present, often at high levels (> 256 up to 10(6) by indirect immunofluorescence on mouse blood smears). The titers are correlated with the severity and the stage of the disease. As double-stranded DNA Ab are rare and as antihistone Ab are frequent, the former could be replaced by the latter in the ARA criteria applied to the SLE dog. Another category of ANAb, named anti-type 1, also seems useful in diagnosing canine SLE. As for therapy, long-term remissions (up to 9 years without treatment) were obtained in 55.6% of 27 SLE dogs treated by levamisole. At first, levamisole was associated with induction corticotherapy, then administered alone and finally discontinued. Side effects were uncommon and transient.

Immunosuppressive property of a very high purity antihaemophilic preparation: a low molecular weight component inhibits an early step of PHA induced cell activation

Immune deficiency has been reported in haemophiliac patients receiving antihaemophilic factor VIII preparations, but the mechanisms involved in the immunosuppression are not fully understood. By using the proliferative response of peripheral blood mononuclear cells to phytohaemagglutinin (PHA) as a test system, we investigated the inhibitory influence of a very high purity antihaemophilic factor (AHF) preparation on T cell proliferation and on T lymphocyte activation molecules. We observed that this preparation reduced significantly the PHA-induced mononuclear cell proliferation, independently of the monocyte concentration. The AHF preparation did not act through a cytotoxic mechanism or a steric hindrance of PHA. The AHF preparation had no effect on the immediate expression of T lymphocyte activation molecules such as CD54 (ICAM-1). In contrast, the very high purity AHF reduced the induced expression of two early T cell activation molecules: CD25 (interleukin-2 receptor) and CD71 (transferrin receptor). The very high purity AHF also had the capacity to inhibit the up-regulation of two late activation antigens, CD38 and CD11a/CD18, and to inhibit the induced expression of HLA-DR molecule, defined also as a late T cell activation molecule. The CD45R expression level, used as a control marker, was not changed after AHF exposure. The very high purity AHF therefore influenced an early step of cell proliferation. We have also shown that the immunoregulatory properties of the preparation were not restricted to the factor VIII itself, but resulted from the presence of dialysable and low molecular weight components in the preparation.

Methylation patterns of long interspersed repeated DNA and alphoid repetitive DNA from human cell lines and tumors

The methylation status of CCGG sites has been determined in long interspersed repeated (L1Hs sequences) DNA and in alphoid satellite DNA extracted from human cell lines and also from pathological specimens. Southern blot experiments were performed using a cloned 1.2 kb KpnI fragment of L1Hs DNA and a cloned 680 bp tetrameric unit of alphoid satellite. DNA as probes for these sequences. In vitro transformation of human lymphocytes by Esptein-Barr virus is correlated with a progressive hypomethylation of L1 Hs DNA sequences. This loss of modification of L1 sequences is also observed in DNA isolated directly from colon adenocarcinoma and in chronic lymphocytic leukemia. Therefore, alteration of the level of methylation of L1 sequences seems not to be due solely to in vitro cultivation of human cells but is associated with the immortalization of these cells. In addition, these sequences are preferentially hypomethylated when compared to alpha-satellite DNA in several lymphoblastoid cell lines and pathological specimens.

[Study of the immune profile of pregnant women]

During pregnancy, the fetus is an hemiallograft perfectly tolerated by the mother. With the aim of elucidating the mechanism of this tolerance, we have looked to see whether lymphocyte subsets are modified by pregnancy. Using monoclonal antibodies and flow cytometry, we have studied the changes in the immune profile of normal pregnant women and compared them with non pregnant women. In pregnant women, a significant decrease in the percentage of CD3+ cells is observed in the first trimester (61.1 +/- 14.7% versus 73.8 +/- 6.8%; p less than 0.001). The same data are obtained for CD4+ cells (38.2 +/- 10.7% versus 44.0 +/- 7.0%; p less than 0.05) and CD8+ cells (22.8 +/- 5.6% versus 28.0 +/- 8.9%; p less than 0.05). On the other hand, B lymphocytes (CD19+), monocytes (Leu M3+) and natural killer (NK) cells (Leu7+) remain stable during pregnancy. CD11a+ cells decreased during the 1st and 2nd trimesters. Lastly, activated T lymphocytes (CD3+DR+, CD8+DR+) are not modified. Using absolute numbers, a significant decrease is shown only for CD3+ cells in the 2nd and 3rd trimesters and for CD11a+ cells in the 2nd trimester of pregnancy. The decrease of T lymphocyte subsets, NK and CD11a+ cells during pregnancy partially explains the tolerance for the fetus.

Demonstration of woodchuck hepatitis virus infection of peripheral blood mononuclear cells by flow cytometry and polymerase chain reaction

Peripheral blood mononuclear cells (PBMCs) from 10 woodchuck hepatitis virus (WHV)-infected woodchucks were examined for the presence of WHV surface (WHs) and core (WHc) antigens (WHsAg and WHcAg) by cytofluorometry using fluorescein isothiocyanate-conjugated anti-WHs and anti-HBc-purified immunoglobulins from woodchuck and human sera. The presence of viral DNA and RNA was detected in the serum and PBMCs from the same blood samples by polymerase chain reaction (PCR) with two primer sets located in the S and C genes of the WHV genome. Seven animals were found positive for both WHsAg and WHcAg on the surface of PBMCs: four WHV-chronic carriers, two WHsAg-positive animals with acute WHV infection, and one woodchuck which was bled during the incubation phase of WHV infection and which became WHsAg-positive only 1 month later. Sixteen to 71% of the studied leukocyte population expressed WHsAg with a low density of expression whereas 7 to 72% expressed WHcAg with a high density of expression. Only two cases were positive for WHsAg without WHcAg on PBMCs, one WHV chronic carrier and one anti-WHs-positive animal. All woodchucks positive for WHcAg and/or WHsAg by cytofluorometry were positive also for WHV DNA and RNA in PBMCs by PCR. The tenth animal was found negative for both viral antigens as well as for WHV DNA and RNA in PBMCs despite the presence of persistent viral DNA in the serum as detected by PCR. Five healthy woodchucks devoid of WHV serological markers served as negative controls. These results obtained with a novel approach further confirm, in the woodchuck model, that a significant proportion of PBMCs are probably permissive for WHV replication. The possible immunopathogenic implications of the phenomenon are discussed.

Expression, function and regulation of the intercellular adhesion molecule-1 (ICAM-1) on human intestinal epithelial cell lines

We have characterized the presence of the intercellular adhesion molecule-1 (ICAM-1) (CD54) on human intestinal adenocarcinoma cell lines as a nonreducible polypeptide of Mr 93 kDa, identified as a rhinovirus receptor. Expression of ICAM-1 was positively correlated with enterocytic maturation, in that the percentage of ICAM-1+ cells was highest in the most differentiated cell line Caco-2. ICAM-1 could be up-regulated only on the less differentiated cell lines HT29 and T84 by phorbol 12-myristate 13-acetate and by the cytokines interferon-gamma (IFN-gamma) and interleukin (IL) 1 beta. Enterocyte ICAM-1 was involved in adhesion to activated T cells through binding to the leukocyte function associated antigen-1 (LFA-1). These data provide evidence that colon adenocarcinoma cell lines express functional ICAM-1 sensitive to cytokine regulation. These findings support the hypothesis that lympho-epithelial interactions involving the ICAM-1/LFA-1 pathway may be implicated in immunosurveillance of colon adenocarcinomas, inflammatory bowel disease and celiac disease, where increased levels of proinflammatory cytokines are locally produced within the gut mucosa.

Dextran sulfate specifically interacts with the human LFA-1 molecule (leucocyte function associated antigen-1)

We have investigated by flow cytometry the action of dextran sulfate (DxS) on the expression of the LFA-1 molecule in human lymphocytes. This work was undertaken because of the involvement of the LFA-1 molecule in HIV-1 induced syncytia and because of the role of DxS played in the inhibition of syncytia formation. Firstly we detected five distinct topographic regions (epitopes) on the LFA-1 molecule with a panel of 11 monoclonal antibodies (Mabs). Then we demonstrated that DxS interacts with some epitopes mainly present on the alpha chain of the LFA-1 molecule. This inhibition on the LFA-1 expressions by DxS occurs after 1-3 hr of incubation of either 4 or 37 degrees C with complete reappearance of LFA-1 within 1 hr of placing cells in fresh medium. In addition both 5 and 500 kDa have been found to have a similar influence on the inhibition of the LFA-1 expression, while non sulfated dextran have no effect. Other sulfated polyanion (SP) such as heparin and chondroitin sulfate have no effect on the LFA-1 expression. Further at 4 degrees C, DxS does not alter the expression of molecules recognized by Mab such as Leu3a (CD4), Leu2a (CD8), Leu4 (CD3) and Leu5b (CD2). However at 4 degrees C, DxS decreases the expression of CD45R molecule which is recognized by Mab Gap8.3. At 37 degrees C, we observe a decrease also in CD4 expression after DxS exposure. It has also been found that DxS decreases LFA-1 expression to the same extent regardless of the basal expression of LFA-1 in each selected cell subset (LFA-1 low, dim or bright). These results suggest that the inhibitory effect of DxS on the HIV-induced syncytium formation could be due partially to a specific steric hindrance of some LFA-1 determinants.

Functional epitope analysis of the human CD11a/CD18 molecule (LFA-1, lymphocyte function-associated antigen 1) involved in HIV-1-induced syncytium formation

After binding to the CD4 receptor, the human immunodeficiency virus 1 (HIV-1) may enter the T cell and induce the formation of multinucleated giant cells (syncytia). As well as the CD4 molecule, other molecules, such as the lymphocyte function-associated antigen 1 (LFA-1, CD11a/CD18) have been shown to be involved in HIV-1-mediated cell fusion. This study was designed to define regions on the human CD11a/CD18 molecule important for the HIV-1-induced syncytium formation. A CD11a/CD18 MoAb panel discriminating at least five distinct and spatially distant domains on the LFA-1 molecule was used. Comparison of the functional activity of different MoAbs demonstrated that all epitopes of the LFA-1 molecule were not of equal importance in HIV-1-induced syncytium formation between H9.III cells chronically infected with HIV-1 and uninfected CD4+ SupT1 cells. We also demonstrated that CD11a/CD18 MoAbs inhibit syncytia formation only at the level of the uninfected SupT1 cells, suggesting that the LFA-1 molecule expressed on SupT1 cells interacts with ligand(s) expressed on the infected H9.III cells. Two potential LFA-1 receptors on the H9.III cells were tested: the ICAM-1 molecule (intercellular adhesion molecule 1, CD54) and the HIV-1 transmembrane glycoprotein 41 (gp41). A CD54 MoAb (84H10) partially inhibited syncytia formation, thus demonstrating the involvement of the ICAM-1 molecule in the HIV-1-mediated cell fusion. However, the CD11a/CD18 MoAbs do not inhibit binding of the viral envelope glycoprotein gp41 to the cell surface, irrespective of the MoAb concentration used. Although we have not been successful in identifying all candidate fusion receptors for the LFA-1 molecule, these data suggest that some LFA-1 regions are important for syncytium formation and, therefore, in the cell-to-cell transmission of virus and in the spread of infection.

Serial transplantation and characterization of a canine diffuse large cell lymphoma grafted in nude mice

A continuous canine lymphoma cell line (DL. 24N) was established by serial transplantation from a diffuse large cell lymphoma into athymic nude mice, yielding subcutaneous tumours at the injection site associated with lymph node metastasis. The transplanted tumour cells, of canine origin as assessed by the karyotype, appear comparable to the large non-cleaved and immunoblastic human cells, as did the initial tumour cells. Immunological studies show reactivity with antibodies to dog immunoglobulins, DT-2 and Thy-1, to MHC-class II antigens, and to both CD10 (CALLA) and CD21 (CR2) human antigens. Such a cell line, showing similarities with some of the human diffuse large cell lymphomas, will thus provide a new tool for further comparative studies of malignant lymphomas.

Proliferation and activation of human mononuclear cells induced by ionomycin in a serum-free medium

Ionomycin was capable of inducing the proliferation and activation of human peripheral blood mononuclear cells (MNC) in serum-free culture medium. Optimal responses, evaluated by tritiated thymidine ([3H]Thy) incorporation and by HLA-DR antigen expression, were obtained with 0.5 micrograms/ml ionomycin in 72-hour cultures. The two ionomycin-induced effects required the presence of monocytes from the start of the culture. It was observed that no cell adhered to the support after three days of culture in the presence of ionomycin, when compared with an ionomycin-free control. The cells stimulated with ionomycin had a large cytoplasm, were metabolically highly active and had a morphology comparable to that of PHA-stimulated cells. At the end of culture, 23 +/- 4% of cells were DR+; this percentage was only partially found (15 +/- 3%) in all the cell populations studied (T and B lymphocytes, NK cells, monocytes). This led us to believe that this expression occurred in other, probably non-differentiated cells. These later were not stimulated to mature by ionomycin. Thus, ionomycin constitutes an essential early signal, but is insufficient to trigger the complete maturation of cells.

Haemolytic disease of the newborn infant. Long term efficiency of the screening and the prevention of alloimmunization in the mother: thirty years of experience

During the last thirty years, the diagnosis, management and prevention of haemolytic disease of the newborn infant (HDN) have improved. From 1959 to 1988, 3004 HDN (ABO excluded) have been collected. The percentage of HDN with anti-D alloimmunization decreased significantly (98.4% from 1959 to 1968, 93.5% from 1969 to 1978 and 68.1% from 1979 to 1988). The anti-D HDN with exchange transfusion (ET) fell significantly between the first and second periods (577 versus 970; chi 2 = 19.92; P less than 0.001). On the other hand, the number of HDN other than anti-D increased during these three periods, but the percentage of these HDN which needed ET decreased. Our study shows the long term efficiency of the prevention of anti-D alloimmunization (since 1970) and of the irregular antibodies screening among all pregnant women (since 1979).

Regulation and functional involvement of distinct determinants of leucocyte function-associated antigen 1 (LFA-1) in T-cell activation in vitro

The expression of leucocyte function-associated antigen 1 (LFA-1) was studied by immunofluorescence method on human peripheral blood mononuclear cells (PBMC) stimulated by the phytohaemagglutinin lectin (PHA). Monoclonal antibodies (MoAb) Mas 191c, IOT18 (directed against the beta-chain, 95 kDa, CD18) and IOT16, SPVL7, MHM24 (identificating the alpha-chain, 180 kDa, CD11a) were used, defining the 'CD11a/CD18' antibody panel. By means of cross-linking or competitive experiments, we showed that these antibodies recognized at least four distinct and spatially distant domains on the LFA-1 molecule. Immunofluorescence analysis revealed that the up-regulation of LFA-1 expression was a late event, similar to the expression kinetics of the HLA DR and CD38 molecules, and followed the appearance of CD25 and CD71 molecules. Moreover, it was established that the LFA-1 up-regulation required mRNA and protein synthesis. Functional activity comparison of the different anti LFA-1 MoAb showed that the CD11a MoAb significantly inhibited the proliferation of lymphocytes stimulated by the phytohaemagglutinin to various extents, as the LFA-1 alpha determinant identified. By contrast, the CD18 MoAb did not influence strongly this cell process. We observed only a dim inhibitory effect with the CD18 MoAb recognizing an epitope common or very close to an LFA-1 alpha determinant. These results suggested that the LFA-1 antigen was important, at a molecular level, in the regulation of T-cell activation.

Phenotypic analysis of a large number of normal human bone marrow sample by flow cytometry

Bone marrow aspirates from 48 healthy donors (34 adults, 14 children) were analyzed by flow cytometry (FACS Analyzer) after purification of low-density bone marrow cells (Ld BMC) on a density gradient (d = 1,077) and labelling with 23 anti-hematopoietic cell monoclonal antibodies. Based on physical properties, these Ld BMC could be divided into four different populations called E, My, Mo and L, which comprised 14% +/- 9%, 31% +/- 16%, 10% +/- 5% and 45% +/- 14% of these cells, respectively. The phenotypic analysis of these different populations enabled the identification in E, of erythrocytes (Glycophorin A+, Rhesus D+, but negative for early erythroid differentiation markers such as the transferrin receptor (Tf. R) and the FA6-152 antigen); in My of cells of the myeloid lineage (VIM2+, HLA DR-); in Mo of cells of the monocytic lineage (VIM2+, CD14+) plus some myeloblasts (VIM2+, CD14-, HLADR+) and finally in L of a heterogeneous population including: 1. T lymphocytes labelled to the same extent by CD2, CD3, CD5 and CD6 (28% +/- 10%), B lymphocytes assessed by CD19 and CD20 (12% +/- 8%), Pre-B cells (CD10+ = 8% +/- 7%), less than 5% of "natural killer" cells (CD16+ or Leu7+) and finally, less than 6% of myelomonocytes (CD14+ and/or VIM2+). 2. The erythroid lineage (rhesus D+ = 42% +/- 20%, Tf.R+ and FA6-152+ = 32% +/- 12%). 3. Undifferentiated cells or progenitor cells (CD34+ = 7% +/- 5%). 4. Cells unlabelled by any antibodies (approximately 6%). We observed no difference between bone marrow samples from adults or children, with respect to physical properties, and with all but four immunological markers. A significantly higher proportion of B cells (CD19+ and CD10+) (P less than 0.001) and undifferentiated cells (CD34+ and HLADR+) (P less than 0.02) was observed in children. These data, obtained from a large number of bone marrow samples, could be used to quantify the imbalance of some bone marrow disorders.

Leukocyte function-associated antigen-1 expression on peripheral blood mononuclear cell subsets in HIV-1 seropositive patients

In order to further investigate immune dysfunctions in HIV-1 infection, we studied the intensity of leukocyte function-associated antigen-1 (LFA-1) expression using a novel application of immunofluorescence analysis in 14 adults and 5 children seropositive for HIV-1 and in 14 healthy adults and 5 healthy children seronegative for HIV-1. While almost all lymphocytes in human peripheral blood expressed LFA-1 and while the percentage of the LFA-1 positive cells was not modified during the course of the HIV-1 infection in both adults and children, our results showed an increase of the LFA-1 expression on selected peripheral blood mononuclear cell subsets. Some LFA-1-labeled functional peripheral blood mononuclear cell subsets such as the CD16, CD14, CD3, and CD8 lymphocyte subpopulations expressed higher levels of the LFA-1 molecule during the HIV-1 infection. The LFA-1 dim cell subsets (CD4 cells) and the LFA-1 low cell subpopulation (CD19 lymphocytes) were not affected by the HIV-1 infection. Moreover, in the CD8 and CD3 cell subsets displaying a heterogeneous LFA-1 expression (dim and bright), we also observed a decrease of the LFA-1 dim/LFA-1 bright cell ratio.

[Spontaneous fluctuation of extracellular matrix molecules on the surface of human skin fibroblasts in culture: flow cytometric analysis]

The evolution of five surface markers (CD 10, fibronectin, collagens I, III, IV) was analysed in cytofluorometry after immunolabelling of cultured human skin fibroblasts. The expression of the CD10 molecule and collagen IV remained stable. On the contrary, there was a spontaneous variation of the cell surface distribution of fibronectin and collagens I and III. This variation was periodical and followed the subculture rhythm. After every passage, the density of matrix components increased at the cell surface. The maximum of the density was achieved on confluent fibroblasts then decreased until the next passage. The fibronectin and collagens I and III expression was permanently altered on senescent fibroblasts. Modifications of the expression of extracellular matrix proteins on the fibroblasts surface were closely linked with cellular density and senescence.

Long-term culture of human bone marrow. I. characterization of adherent cells in flow cytometry

Using long-term culture techniques, we were able to characterize the different adherent cell elements of the in vitro bone marrow microenvironment by flow cytometry. After 2 weeks of culture, four adherent cell subsets, L, MM, F, and M, were distinguished according to their intrinsic cellular characteristics of volume and spontaneous fluorescence. Using four immunological markers, we identified each population as a hematopoietic lymphocytic group (L), CD45+, VIM2-, CD14-; a hematopoietic myelomonocytic group (MM), CD45+, VIM2+, CD14-; a hematopoietic macrophage group (M), brightly autofluorescent, CD45+, VIM2-, CD14+; and a group of fibroblastoid cells (F) with a very high volume, CD45-, VIM2-, CD14-, and collagen III+. Isolation of the different hematopoietic and nonhematopoietic components of long-term bone marrow culture is thus possible using flow cytometry analysis according to the cell characteristic of volume and spontaneous fluorescence alone.

Systemic lupus erythematosus in dogs: association to the major histocompatibility complex class I antigen DLA-A7

The DLA-A,B antigens and the allotypes of the fourth complement component have been determined in German shepherd dogs suffering from systemic lupus erythematosus. We have typed 26 unrelated affected dogs, 11 animals of a three generation family, and 16 dogs of a colony with a high frequency of the disease. The results obtained from the 26 unrelated diseased dogs were compared to those determined in the 23 unaffected German shepherds. The antigen DLA-A7 was found to be predominant in the diseased group with a c2 = 11.02, Pc = 0.02, and a relative risk for the carriers of 11.93. The antigens DLA-A1 and DLA-B5 were negatively associated to the disease (c2 = 14.95, Pc = 0.001, and c2 = 17.16, P = 0.0008 respectively) and thus may be of protective nature. These data were further substantiated by the typing of the three generation family and the colony.

Differential expression of the LFA-1 molecule on the human peripheral blood mononuclear cell subpopulations

The expression of leukocyte function associated antigen 1 (LFA-1) was studied on human peripheral blood mononuclear cells (PBMNC) by a double immunofluorescence method. Monoclonal antibodies IOT18 (recognizing the beta chain, 95 kDa, CD18) and SPVL7 (recognizing the alpha chain, 180 kDa, CD11a) were used. These antibodies revealed the same heterogeneous distribution of the LFA-1 molecule among peripheral blood mononuclear cells. A bimodal profile characterized the lymphocytes, whereas the monocyte subpopulation presented a unimodal profile. NK cells, including CD16, CD8 dim, expressed the LFA-1 with a high density. B cells expressing the CD19 phenotype showed surface LFA-1 at a low level, whereas it appeared with an intermediate intensity on the T helpers/inducers (CD4 cells). Among the cytotoxic cells (CD8) and the immunoregulatory subpopulations associated with an immunosuppressive response (CD8+ CD11b+, CD8+ CD11b- and CD8+ leu8+) or with a contrasuppressive response (Vicia villosa cells), an heterogeneous LFA-1 expression was observed, discriminating the LFA-1 dim and the LFA-1 bright cells. Anti LFA-1 antibodies also allowed us to define three novel subsets among the CD8 cells: the CD8 dim LFA-1 bright, the CD8 bright LFA-1 bright, and the CD8 bright LFA-1 dim cell subpopulations. This heterogeneous distribution of LFA-1 among PBMNC may be associated with different functions of the different cell subsets analyzed in this study.

The gel test: a new way to detect red cell antigen-antibody reactions

A new process for the detection of red cell (RBC) antigen antibody reactions is described. It is applicable to most of the tests performed in blood group serology. The procedures are standardized and easy, and they provide clear and stable reactions that improve the interpretation of results. The process uses special microtubes filled with a mixture of gel, buffer, and reagent. Depending on the test to be carried out, the test uses a neutral gel containing no reagents (reagents are added to top of gel) or a specific gel containing reagents (e.g., antiglobulin serum or anti-A, -B, -D, etc.). A suspension of RBCs (for typing or the direct antiglobulin test) or a mixture of RBCs and serum (for reverse ABO typing or antibody characterization) is centrifuged through the gel under precise conditions. In negative reactions, the RBCs pass through the gel and pellet in the bottom of the tube, whereas, in positive reactions, they are trapped in the gel and the reaction may be read for hours afterwards. The test is easy to perform, sensitive, and reproducible. The antiglobulin tests can be performed without washing of the RBCs. There should be a reduction of risk from biohazardous materials.