Suppression of acute secondary disease by heterologous anti-brain serum.

Antisera raised in rabbits against murine brain contained antibodies against thymocytes and bone marrow cells of mice. While cytotoxic tests revealed only low titer antibodies against B-cells, complement fixation, plaque-forming and colony-forming tests demonstrated little difference in antibody activity against T-or B-cells. Absorption of anti-brain serum with liver and plasmocytoma cells led to residual specific anti T-cell activity. Incubation of these absorbed anti-brain sera with parental spleen cells before transplantation into lethally irradiated H2incompatible F1 hybrids suppressed acute secondary disease. While all the controls died of acute secondary disease, about 90% of the recipients of spleen cells treated with anti-brain serum survived day 100 post transplantation, without showing any wasting

Polyacrylsäure-Kügelchen als Nachweis von B-Lymphocyten.

B-Lymphocyten können durch ihre Eigenschaft, Polyacrylsäure-Perlen anzulagern, charakterisiert werden. Die Methode wird an verschiedenen Zellpopulationen auf ihre Spezifität und Reproduzierbarkeit untersucht

Independent expression of the surface markers 5′-nucleotidase and cALLA on leukemic cells.

High levels of the ectozyme 5′-nucleotidase (5′-N) and the common ALL-antigen (cALLA) are coexpressed on leukemic blast cells in common ALL, in the lymphoid blast crisis of CML and also on the lymphoblastoid cell-line Nalm-1. Clinically this coexpression can help to subclassify leukemias and may be of diagnostic and prognostic significance. In an attempt to study the mechanism underlying this simultaneous expression plasmamembrane subfractionation was undertaken on Nalm-1. When membrane-shedding from intact cells is induced by sublytic concentrations of the lysophosphatidyl-choline analogue ET-12-H, membrane subfractions are obtained which contain 30-40% of total cellular 5′-N, which is most of the enzyme carried on the cell surface, in a highly enriched form. Under these conditions only a very low release of intracellular enzymes is observed. On the other hand cALLA is not accumulated in these membrane fractions to any appreciable extent. The predominant part of this antigen is still on the intact cells remaining after the shedding procedure. It is concluded that the simultaneous expression of 5′-N and cALLA on Nalm-1 and leukemic blasts is not regulated by a physical association or a close neighborhood of these antigens on the membrane level

Production of antibodies specific for human thymus derived lymphocytes purified from antibodies crossreacting with colony forming cells.

Antisera raised in rabbits against human thymocytes contain antibodies against peripheral lymphocytes of normal persons, patients with chronic lymphatic leukemia (CLL) and lymphoblastoid cell lines. Absorption of antithymocyte serum with CLL lymphocytes and spleen preserved the antibody activity against normal peripheral lymphocytes and a lymphoblastoid cell line of T cell type (MOLT 4), while eliminating antibodies reacting with CLL lymphocytes and a B cell type lymphoblastoid cell line (RPMI 1788). The incubation of human bone marrow cells with not absorbed anti thymocyte globulin reduced considerably the number of stem cells committed to granulopoietic differentiation (CFU C). No reduction of CFU C, however, was observed with specifically absorbed anti thymocyte globulin. The possible application of stem cell sparing, purified anti thymocyte globulin for the suppression of graft versus host reactions in human bone marrow transplantation is discussed

Serological analysis of xenogeneic anti-lymphoblastoid cell-line sera with specificity against HLA-B12.

In view of the importance of potent anti-HLA sera with narrow reaction patterns against defined HLA antigens, two xenogeneic antisera were raised in rabbits following immunization with human lymphoblastoid cell lines from HLA-nonidentical donors homozygous for HLA-B12. After absorption with lymphoblastoid cell lines of an appropriate HLA phenotype, the antisera were purified over DEAE-cellulose ion exchange chromatography and reconcentrated. Both antisera recognized HLA-B12-positive peripheral blood cells of unrelated donors tested in the microcytotoxicity assay. The two rabbit antisera revealed a high degree of similarity in their anti-HLA-B12 antibody specificity. One antiserum showed some cross reactivity with HLA-B13 as has been reported in allo-anti-HLA-B12 sera. The other antiserum revealed some activity against HLA-DRw7-positive donors. Antibody activity could be removed completely from two further rabbit anti-HLA antisera by absorption with lymphoblastoid cell lines from related and unrelated HLA-identical donors. The advantages of using lymphoblastoid cell lines as immunogens and absorption material for the production of heterologous anti-HLA typing sera are discussed

Quantitative immunoautoradiography at the cellular level. I. Design of a microphotometric method to quantitate membrane antigens on single cells using 125I-labeled antibodies.

Iodine-125 has become a commonly-used radioisotope, especially for immunoautoradiographic investigations. Microphotometry of grain density, a well-established method in autoradiography with tritium and carbon-14, was applied to nucleated cells with 125I-labeled membranes. Geometric and absorption factors of radiation were investigated in order to find suitable conditions for quantitative evaluation. A preparatory device is given and a set-up of appropriate measuring conditions is presented. With these prerequisites the reflected-light bright-field photometry of immunoautoradiographs permits to determine automatically the content of surface antigens of single cells. Measurement examples were demonstrated