Independence of H-2K and H-2D antigenic determinants on the surface of mouse lymphocytes.

At 37 degrees C, fluorescein-conjugated anti-H-2 alloantibodies specifically induce, at the surface of living mouse lymphocytes, the redistribution of the corresponding H-2 antigens, which cluster as patches and sometimes single caps at one pole of the cell. This aggregation is inhibited at 0 degrees C and the H-2 antigens, stained by fluorescent antibodies in the cold, appear evenly spread over the cell surface. This phenomenon was used to define the relationships between the membrane structures bearing the antigens coded by the H-2K and the H-2D genes of the H-2 region. Monospecific anti-H-2 antibodies coupled to either tetramethyl rhodamine isothiocyanate or fluorescein isothiocyanate were used to induce the redistribution of H-2D and H-2K antigens of the H-2(b) and H-2(k) haplotype at the surface of lymph node cells from homozygous and F(1) hybrid mice. It was observed that the diffuse distribution of H-2K antigens labeled at 0 degrees C was not affected by the prior antibody-induced aggregation of H-2D antigens and vice versa. The results were the same for H-2 antigens governed by genes located either in cis or in trans position. These data indicate that the H-2K and H-2D antigens migrate independently at the cell surface, and suggest that the gene products from the D and the K end of the H-2 region are expressed on independent molecules or structures at the cell membrane.

Relationship between HL-A antigens and beta-2-microglobulin as studied by immunofluorescence on the lymphocyte membrane.

The antibody-induced redistribution of beta2-microglobulin (beta2-micro) and HL-A antigens on the surface of living lymphocytes was studied by immunofluorescence. When all beta2-micro was redistributed on the lymphocyte membrane by specific rabbit antibodies and goat antirabbit Ig conjugates, the HL-A antigens were no more detectable with anti-HL-A conjugates outside the beta2-micro caps already formed. However, the redistribution of HL-A antigens fails to provoke the redistribution of all detectable beta2-micro molecules. These results suggest that HL-A antigens may be associated with beta2-micro at the cell surface, but that all beta2-micro molecules are not bound to HL-A antigens.

IgG4 subclass in malignant melanoma.

Three hundred and ninety-seven sera from 185 melanoma patients were studied. These sera were classified into three groups according to stage of disease. An alteration in the level of the IgG4 subclass was found. It was related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in patients with stage II and III diseases (55 and 53%, respectively) than in patients with stage I(19%). The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biologic significance of the increase of IgG4 in melanoma remains obscure. The increase may be related to the development of facilitating antibodies of the IgG4 subclass.

Transformation of LMTK- cells with purified HLA class I genes--IV. A determinant on beta 2-microglobulin is controlled by HLA heavy chain in a mouse-human hybrid complex: a biochemical analysis.

Transformation of LMTK- murine fibroblast cells with purified HLA class I heavy chain genes resulted in the expression of serologically detectable HLA-A3 molecules. Surprisingly, such cells also react with a murine monoclonal antibody specific for a serological determinant notably not expressed by murine but by human beta 2-microglobulin. The human HLA molecules expressed by the transformed cells were characterized on two-dimensional gels. The heavy chain was shown to be associated with a murine beta 2-microglobulin molecule, which could be distinguished from human beta 2-microglobulin by its higher isoelectric point. This heterodimer molecule was immunoprecipitated with the mouse anti-human beta 2-microglobulin monoclonal antibody showing that indeed the complex of mouse beta 2-microglobulin and human heavy chain expresses a human beta 2-microglobulin determinant.

Quantification by flow cytofluorimetry of HLA class I molecules at the surface of murine cells transformed by cloned HLA genes.

A method allowing quantitative analysis of the expression of foreign antigens at the surface of transformed cells is described. Aminoethyl-Sephadex G-25 beads labelled with different amounts of fluorescein isothiocyanate (FITC) were used to calibrate an Epics V cell sorter. The quantity of FITC molecules bound per bead was found to be a linear function of relative fluorescence intensity expressed by channel number for intermediate and high levels of fluorescence and a non-linear function for low levels. The lowest limit of detectable fluorescence was 3400 FITC molecules bound per bead. Using FITC-conjugated monoclonal antibodies (m.Ab.) the number of HLA class I molecules expressed at the surface of murine LMTK- (H-2Kk) cells transfected by cloned HLA class I genes was estimated and compared with the amount expressed on human B (Raji) and T (MOLT 4) lymphoblastoid reference cells. Murine transformed cells expressed approximately 3 times less HLA class I determinants per surface unit (micrometer 2) than Raji cells and 1.4 times less than MOLT 4 cells. Similar results were obtained by Scatchard analysis of the same populations using radiolabelled m.Ab. A detailed analysis of fluorescent cells showed that 5-20% of transformed cells expressed less than 33,000 HLA class I molecules/cell whereas most MOLT 4 cells exhibited at least 280,000 molecules/cell and the majority of Raji cells more than 700,000 molecules/cell. The expression of foreign antigen did not reduce the amount of H-2Kk molecules at the surface of transformed cells (mean of 350,000 molecules/cell).

Epitopic analysis of detergent-solubilized HLA molecules by solid-phase radioimmunoassay.

A solid-phase radioimmunoanalysis of plasma membrane molecules solubilized in the presence of detergent was developed. From a crude cell lysate, membrane molecules were specifically immobilized by solid-phase adsorbed monoclonal antibodies. Analysis of these molecules was easily performed with radiolabeled monoclonal antibodies of different specificities. This technique was used to analyze the HLA-DR and HLA-A,B,C molecules expressed by RAJI cells. It was possible (a) to determine which epitopes are expressed on the same molecules; (b) to define subsets of HLA molecules according to the epitopes which they express, and (c) to perform quantitative analysis of HLA molecules on a crude cell lysate.

A 55,000 Mr surface antigen on activated human T lymphocytes defined by a monoclonal antibody.

A T cell growth factor-dependent alloreactive human T cell line has been used to generate a monoclonal antibody B1.49.9 that reacts with an antigen present on most if not all mitogen or alloantigen activated T cells but not on resting T cells. The T lymphoblastoid cell line HUT-102 is also strongly reactive with B1.49.9 but all other T and non-T leukemia-lymphoma cell lines tested were negative. The B1.49.9 antigen is a glycoprotein of 55,000 Mr on mitogen or alloantigen activated T cells and 50,000 Mr on the cell line HUT-102. Pulse labeling experiments showed that a 40,000 Mr precursor (at approximately 0.7 h) which does not bind to ricin lectin precedes the appearance of the ricin-binding 55,000 Mr form. Comparisons of the monoclonal antibody anti-Tac, which recognizes the IL-2 receptor, to B1.49.9 suggest that B1.49.9 also recognizes a structure similar or identical to the IL-2 receptor.

[Comparative study of anti EBV antibodies in non-Hodgkin's lymphomams and angio-immunoblastic lymphadenopathies (author's transl)]. / Anticorps dirigés contre le virus d'Epstein Barr. Etude comparative au cours des lymphosarcomes et des adénopathies angio-immunoblastiques.

Antibody titers to Epstein-Barr virus (EBV)--related antigens (viral capsid antigen : VCA; early antigen : EA; and EBV associated nuclear antigen : EBNA) were determined in the sera of 86 patients and 150 matched control subjects. The patients belonged to four histological groups : diffuse and nodular non-hodgkin's lymphomas angio-immunoblastic lymphadenopathies and apparented syndroms. The incidence of antibodies to other herpes-viruses (cytomégalovirus, herpes simplex virus, and varicella zoster virus) was compared. There was a significantly higher incidence of anti VCA and anti EA titers in some patients, not associated with an increase in titres of antibodies to other herpes viruses.

[IgG levels in the sera of melanoma patients (author's transl)]. / Etude des IgG dans les sérums des sujets porteurs de mélanomes.

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG 4 sub-class was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.

[IgG levels in the sera of melanoma patients (author's transl)]. / Etude des IgG dans les sérums de sujets porteurs de mélanomes.

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG4 subclass was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.