Restriction fragment length polymorphism of DP genes defines three new DP alleles.
Explore the source record for details and available documents.
Alleles↗
Biomedical subjects
A Urlacher
Publications and source records attributed to A Urlacher.
[Anti-HLA immunization following transfusions of leukocyte-poor blood].
We have followed the evolution of leucocyte antibodies in patients receiving multiple blood transfusions of leucocyte-poor blood. The number of leucocytes present in one unit of transfused blood was always less than 1 X 10(8). We observed that such preparations were able to re-stimulate antibodies which had disappeared, but especially they were able to provoke a first immunisation in some patients never immunized in the past. The specificities of these antibodies corresponded to one or several antigens present in the donor of the transfused unit. This study shows that leucocyte immunisation cannot always be avoided in spite of the selection of blood products containing very few white cells.
Adolescent↗
HLA class I antigens on normal and leukemic cells (quantitative analysis).
A monomorphic anti-Class I monoclonal antibody, ST01, found in our laboratory, was used to quantify Class I antigens on normal and leukemic cells, using a "CELISA" technique. Saturation graphs were used to compare the quantity of Class I antigens on normal PBL (25 cases) with that on the following types of leukemic cells: a) common acute lymphoblastic leukemias (cALL) (11 cases), b) mature B lymphocytic proliferations (16 cases), c) T hemopathies (9 cases), d) non-lymphoid leukemias (9 cases). In most cases the quantity of HLA Class I antigens was greatly reduced. No correlation was found between the quantitative expression of Class I antigens and the stage of maturation in each cell type, nor was any correlation found between the quantitative expression of Class I antigens on the leukemic cells and the proliferation of leukemic cells in the peripheral blood.
B-Lymphocytes↗
New human MHC class I antigens segregating with HLA-A antigens detected on some lymphocyte subpopulations.
Recent genetic studies of the murine chromosome 17 have demonstrated that many genes encode class I antigens, most of which are still not detected serologically; most of these genes belong to the Tla region. Five human alloantisera were selected from 383 female sera and were further studied using a panel of peripheral blood lymphocytes (PBL), B lymphocytes (BL), and PHA activated lymphocytes (PHA-L) from the same blood donors. After intensive platelet absorption, the five sera still reacted positively by a complement-dependent cytotoxicity technique with PHA-L, but negatively with PBL and BL. The antigens detected by these antibodies segregated with an HLA-A allele and were assumed to belong to the class I antigen series as they could be blocked by a turkey anti-beta 2 microglobulin serum. They were found on some lymphocyte populations: PHA-L, common acute lymphoblastic leukemia (cALL) cells, and (preliminary results) a small subpopulation of PBL cells (mostly NK cells), but were not found on chronic lymphocytic leukemia (CLL) cells, T and early T acute lymphoblastic as well as myeloblastic leukemia cells. Kinetic studies showed that several hours of culture with PHA were necessary for the antigen to be expressed. These results show that the antigens described do not belong to the classic HLA antigen series but could be considered to belong to the human Qa-like antigens or to be the human counterpart to the second murine H-2K locus antigens.
Antigen-Antibody Complex↗
[Expression of class I and class II markers on populations of leukemic cells].
The study of class I and class II antigen expression on leukemic cells brought the following conclusions: most of the leukemic cells show a slower number of class I antigenic sites than normal peripheral blood lymphocytes (PBL) but, in most cases, this does not hinder HLA typing; contrarily to normal PBL, leukemic cells seem to carry "non HLA" antigens (and/or non classical HLA antigens) which are probably responsible of the false positive reactions frequently observed at the time of HLA typing; most of the leukemic cell types express DR antigens (except those belonging to the T lineage) but DQ antigen expression (and in some cases MT antigen expression) varies depending on the cell type studied: well defined on mature B hemopathies, DQ expression is often lower than DR expression on acute leukemic cell types.
HLA Antigens↗
Abnormalities of in vitro responses to polyclonal activation of peripheral blood lymphocytes in patients with active sarcoidosis.
A variety of immunological abnormalities have been described in patients with sarcoïdosis. At the blood level, both hypo and hyper immune responsiveness seem to coexist and were related to abnormal T cell and macrophage functions by using allogenic cocultures and/or lymphocyte fractionation. We tested several components of cell mediated responses with two in vitro models: (a) the pokeweed mitogen activation of B cells which is T cells and macrophage dependent; (b) the Epstein-Barr virus (EBV) activation of B cells which is T cell- and macrophage-independent. We confirm previous data showing that PWM induced Ig Production of peripheral blood lymphocytes (PBL) of patients with sarcoïdosis is significantly reduced compared with normal PBL. However, this is associated with an increase of IgG, IgM synthesis of EBV-infected PBL in these sixteen patients. Thus, there is no evidence for a complete B cell defect in sarcoïd PBL. Furthermore, by using limiting dilution analysis of antibody secreting cells, there is an increase of precursor B cells EBV infectable in PBL of sarcoïd patients but T cells are effective in reducing EBV-induced B cell proliferation. Finally, these abnormalities are concomitant to the disease, disappear with it, and are apparently not correlated with the stage or the activity of sarcoïdosis.
Adult↗
Natural HLA antibodies.
"Natural antibodies" directed against antigens of the Major Histocompatibility Complex have been observed in aged mice but very seldom in humans. It is likely that HLA natural antibodies are more common than previously supposed: our results suggest they may be found in 1% of normal blood donors. Most of these antibodies seem to be weak and can only be detected when B lymphocytes (BL) are used as target cells in the lymphocytotoxicity technique or when indirect immunofluorescence is used with peripheral blood lymphocytes (PBL). The behavior of these natural IgM antibodies was compared to that of weak immune IgG HLA antibodies detected in the same way. Absorption tests showed that "natural antibodies" were very specifically absorbed, whereas "immune antibodies" could also be absorbed by cells not carrying the specific antigen. Furthermore, about half of the "natural antibodies" detected to date carried the HLA-B8 specificity. Various hypotheses have been put forward to attempt to explain the appearance of these antibodies.
Adult↗
[ELISA on cells. Review of current technics].
Immunoenzymological techniques are used to detect monoclonal antibodies directed against cell membrane antigens. The different materials used, the method of utilizing cells, the choice of the appropriate enzyme and the different technical variations are described. The advantages and disadvantages of each method are discussed.
Animals↗
Inhibition by DL-alpha-difluoromethylornithine of the pokeweed mitogen-induced immunoglobulin production in cultured human lymphocytes.
The effects of DL-alpha-difluoromethylornithine (DFMeOrn), an irreversible inhibitor of L-ornithine decarboxylase, on immunoglobulin production were studied in vitro using human peripheral blood lymphocytes stimulated with pokeweed mitogen. DFMeOrn inhibits in a concentration-dependent manner the usual pokeweed mitogen-induced increases of polyamine contents (putrescine, spermidine, spermine) and of [3H]thymidine incorporation. In parallel with the reduction of polyamine content and of thymidine incorporation, IgG and IgM productions are diminished, a 70% decrease being observed at 5 mM DFMeOrn concentration. Therefore, it appears that inhibition of polyamine biosynthesis may ultimately interfere with the cellular immunologic response by blocking cell proliferation. These findings certainly deserve further consideration both under in vitro and in vivo conditions.
Cells, Cultured↗
Idiotypic network: possible explanation of seronegativity in a patient with rheumatoid arthritis.
In order to explain long term seronegativity in certain patients with rheumatoid arthritis (RA), we looked for the presence of anti-idiotypic antibodies against rheumatoid factors (RFs). From a patient's serum with classical but seronegative RA, we isolated a low quantity of the IgG fraction which partially recognized polyclonal RF idiotypes. The purified Fab'2 anti-idiotypic antibodies were able to inhibit up to 48% of in vitro RF production by pokeweed mitogen stimulated lymphocytes from a patient's peripheral blood with seropositive RA. The two main conclusions of this study are: (1) this single patient with seronegative RA has serum antibodies directed against RF idiotypes and (2) these anti-idiotypic antibodies could be implicated in the generation of seronegativity.
Adult↗
A highly conserved determinant on human rheumatoid factor idiotypes defined by a mouse monoclonal antibody.
Different human IgM rheumatoid factor (IgM RF) idiotypes have been described defined by polyclonal rabbit anti-idiotypic antibodies. These antisera do not allow clear genetic analysis of the idiotypic determinants, be they cross-reactive or private. Therefore, we tried to obtain a set of monoclonal anti-idiotypic antibodies directed against RF idiotypes. Purified IgM RF serum from a patient with classical rheumatoid arthritis was used to immunize BALB/c mice. The spleen cells were fused with Sp 2/0 Ag 14, a nonsecreting mouse myeloma cell line, and a hybrid producing monoclonal anti-idiotypic antibody was selected. The mouse antibody, an IgG1 kappa, reacts with an identical or similar determinant located on (or close to) the binding site of all tested monoclonal or polyclonal IgM RF from totally unrelated patients with Waldenströms's macroglobulinemias or rheumatoid arthritis. The monoclonal antibody also reacts with 2 rheumatoid arthritis patients' IgG RF and with a low proportion of normal polyclonal IgM without detectable RF activity. An hypothesis is proposed to explain the existence of a such highly conserved determinant on RF idiotypes.
Animals↗
[In vitro lymphocyte stimulation by the pokeweed mitogen in normal subjects and undernourished patients. Influence of ornithine salts].
The influence of different concentrations of ornithine phosphate and ornithine alpha ketoglutarate on pokeweed mitogen stimulation of immunoglobulin production in vitro was tested. Lymphocyte response of normal subjects was compared with lymphocyte response of undernourished patients. Our results indicate that IgG and IgM synthesis, under usual culture conditions of PWM stimulation, can be optimized in certain normal subjects by adding low concentrations (10(-5)M/l) of ornithine in culture medium. Moreover, in this culture system, the deficit observed in undernourished patients can be partially corrected by adding physiological (close to serum) concentrations of ornithine. More data are necessary in order to find out in vivo the effect of administration of ornithine on the immune system which is influenced by many (specially hormonal) factors.
Humans↗
Influence of recombinant interleukin-2 and alpha- and gamma-interferons on the induction of novel class I antigens.
Previous results obtained in our laboratory showed that novel class I antigens, closely related to HLA-A (TM antigen related to HLA-A9 and GO antigen related to HLA-A24), were expressed on activated HLA-A9 or HLA-A24 peripheral blood lymphocytes (PBL), whatever activation factor was used [mitogenic stimulation (PHA, PWM, Con A), EBV transformation or alloactivation], but not on resting T and B lymphocytes. These antigens were also expressed on HLA-A9 or HLA-A24 common acute lymphoblastic leukaemias (cALL) and some 'immature' chronic lymphocytic leukaemias (B-CLL), but not in hairy cell leukaemias (HCL), most of the B-CLL, acute myeloblastic leukaemias (AML) and acute myelomonoblastic leukaemias (AMoL). In order to investigate the regulation mechanisms of these novel class I antigens, PBL and different leukaemic cell types were treated in vitro with recombinant IL-2 (rIL-2) and alpha and gamma-interferon (rIFN). Our results showed that without previous activation, but after culture with rIL-2, TM and GO antigens could be induced in HLA-A9 or HLA-A24 PBL and enhanced in HLA-A9 or HLA-A24 B-CLL cases, whereas no expression was found in HLA-A9 or HLA-A24 HCL, T-ALL, AML or AMoL. After culture with rINFs, the expression of TM and GO antigens could be induced on HLA-A9 PBL and all HLA-A9 leukaemic cell varieties. Our results support the hypothesis that the expression of class I antigens is induced at an early stage of the cell cycle.
Cell Cycle↗
Analysis of HLA specificity of human monoclonal antibodies by cytofluorimetry and cell ELISA.
In this study we report on the characterization of cytotoxic human monoclonal antibodies (HmAb) detecting polymorphic HLA class II specificities using cytofluorimetric analysis in combination with micro cell ELISA. In both techniques, five anti-HLA HmAb were tested against HLA-transfected murine L cells as target cells and the bound antibody was detected, either by cytofluorimetry or by cell ELISA reader, after addition of fluoresceinated or peroxidase-conjugated anti-human IgG+IgM antibodies, respectively. The results demonstrate that HmAb directed against HLA-DR, -DQ and -DP molecules can be efficiently discriminated by cytofluorimetry and cell ELISA, which appear to be highly sensitive and perfectly comparable to the standard cytotoxicity assay.
Animals↗