Stephen P. Hauptman

Suppressor cell population in Sézary syndrome

Abstract In the present study, T lymphocytes from a patient with the Sezary syndrome were shown to suppress the synthesis of immunoglobulin in B lymphocytes. Immunoglobulin synthesis and secretion were measured in cultures containing lymphocytes and pokeweed mitogen. Although normal peripheral blood lymphocytes synthesized immunoglobulin in vitro, lymphocytes from the Sezary patient were incapable of immunoglobulin synthesis. After fractionation of normal and Sezary lymphocytes into T- and B-cell populations, immunoglobulin synthesis was demonstrated in cultures containing normal T and Sezary B cells, but not in cultures of Sezary T and normal B cells. When Sezary T lymphocytes were cocultured with both normal T and B cells, immunoglobulin synthesis was suppressed by 80%, compared to appropriate controls. These studies demonstrate that malignant transformation of T lymphocytes in the Sezary syndrome can result in the generation of cells which suppress immunoglobulin synthesis. Furthermore, B cells from this patient were capable of synthesizing immunoglobulin, predominantly IgA, in the presence of normal T cells.

T-cell abnormalities in inflammatory bowel disease are mediated by interleukin 2.

Inflammatory bowel disease (IBD) may be an immunologically mediated disorder in which T cells are unable to respond appropriately to cell surface-associated antigens. To test this possibility, 37 patients with IBD, 24 with Crohns disease and 13 with ulcerative colitis who were not being treated with immunosuppressive therapy were studied. The ability of T cells to proliferate in response to autologous or allogeneic cells, i.e., the autologous or allogeneic mixed-lymphocyte reaction (MLR) was tested. The autologous MLR was depressed using patient cells compared to control cells, regardless of disease type or activity (1564 +/- 223 cpm versus 3300 +/- 381 cpm, P less than 0.05) while the allogeneic MLR was depressed in patients with active disease only (29,833 +/- 2871 cpm versus 46,799 +/- 3340 cpm, P less than 0.01). The ability of T cells to recognize and lyse allogeneic cells, allogeneic cell-mediated lympholysis (CML), was also low in patients with active disease (24 +/- 4% versus 37 +/- 3%, P less than 0.05). Since T-cell proliferation and cytotoxicity depend upon adequate production of and response to a T-cell growth factor, interleukin 2 (IL-2), IL-2 production and responsiveness in IBD were studied. IL-2 production by patient T cells in response to phytohemagglutinin was only 39% of control values, P less than 0.05. The response to IL-2 was measured by the increase in T-cell proliferation in the autologous MLR in medium alone or medium supplemented with IL-2. Control T-cell proliferation rose from 3300 +/- 381 cpm to 10,761 +/- 428 cpm with exogenous IL-2 (P less than 0.001). Patient T-cell proliferation rose from 1564 +/- 223 cpm to 6817 +/- 771 cpm with IL-2 (P less than 0.001) but did not reach the level of the IL-2-supplemented control autologous MLR (P less than 0.05). In addition, the percentage of activated patient T cells having Tac antigen (IL-2 receptor) was depressed (P less than 0.05). These findings did not vary with disease type or activity. It is concluded from these data that peripheral blood T lymphocytes from patients with IBD have a diminished response to cell surface antigens which is associated with a decrease in IL-2 production and receptor generation. These defects may be responsible for the depressed T-cell proliferation and cytotoxicity that accompany IBD.

Chronic Lymphocytic Leukemia Cells Lack the 185,000-Dalton Macromolecular Insoluble Cold Globulin Present on Normal B Lymphocytes

We have recently characterized two lymphocyte-associated membrane proteins which have been termed 225,000-dalton and 185,000-dalton macromolecular insoluble cold globulin (225-MICG and 185-MICG, respectively) to distinguish their major physicochemical properties. These proteins differ antigenically, structurally, and in their cellular distribution. T cells can be distinguished by the synthesis and presence in the plasma membrane of 225-MICG, Null cells by the appearance of 185-MICG, and B cells by the appearance of both 225- and 185-MICG. The characterization of these two proteins in the monoclonal B lymphocytes of chronic lymphocytic leukemia forms the basis of this report. Using immunofluorescent microscopy, we found only 225-MICG on the surface of chronic lymphocytic leukemia (CLL) cells in 15 patients, whereas control B cells from 20 individuals displayed both 225- and 185-MICG. When MICG proteins were isolated and compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, normal B cells showed two stained bands, corresponding to 225- and 185-MICG, whereas the CLL cells demonstrated only the 225-MICG band. Using labeled amino acid incorporation into cellular protein, normal B cells were shown to synthesize 225- and 185-MICG, whereas CLL cells synthesized only 225-MICG, as determined by immune or cold precipitation of labeled cell lysates. When labeled secretions from B cells and CLL cells were analyzed by immune precipitation, 225- and 185-MICG were secreted by B cells, whereas neither protein was secreted by CLL cells. When normal B cells and CLL cells were mixed, incubated, and lysed together, both 225- and 185-MICG were present, thus excluding proteolysis as a cause of the absence of 185-MICG in CLL. The lack of 185-MICG in CLL distinguishes leukemic cells from normal B lymphocytes. Furthermore, the absence of this normal cell surface protein in these leukemic cells suggests a role for 185-MICG in the malignant transformation of lymphocytes.

Macromolecular insoluble cold globulin (MICG): a novel protein from mouse lymphocytes--I. Isolation and characterization.

Abstract Murine thymus and spleen cells synthesize a 225,000 dalton macromolecule (MICG). This protein is insoluble in the cold in non-ionic detergents and migrates as a β-globulin on electrophoresis. MICG can be isolated by a two-step procedure consisting of cold precipitation of cellular lysates in NP-40, followed by gel chromatography in detergent solution. Thymocytes synthesized three times more MICG than splenocytes. Immunological analysis demonstrated that anti-MICG antiserum reacted with the cold insoluble protein. Trypsin digestion of radiolabeled, isolated MICG illustrated the incorporation of 14 C-leucine into a number of peptides. MICG is a glycoprotein which accounts for 3.5% of the protein synthesized in thymus cells and is not secreted from thymocytes or spleen cells.

Macromolecular insoluble cold globulin (MICG): A novel protein from mouse lymphocytes—II: T-cell origin of MICG and response to mitogens

Abstract Macromolecular insoluble cold globulin (MICG) is synthesized selectively by mouse T-cells. In support of this conclusion is evidence derived from mitogenic stimulation of thymic and splenic lymphocytes. PHA and Con A stimulated a disproportionately large increase in MICG compared to total protein synthesis in spleen and thymus cells, while IgM synthesis in spleen cells only rose parallel with the increase in total protein synthesis. In LPS-treated spleen cells, MICG synthesis rose only in proportion to total protein. Therefore, selective enhancement of MICG synthesis, i.e. as a proportion of total protein synthesis, only occurred under conditions where T-cells were activated. In the presence of complement, antibody to MICG was cytotoxic to virtually all thymocytes and half of the spleen cells. Furthermore, antibody to MICG eliminated the mitogenic effect of PHA and Con A on spleen cells, while the response of these lymphocytes to LPS was normal. Cytotoxicity with antibody and complement also caused a significant diminution of MICG synthesis in spleen cells. Finally, isolated T-cells demonstrated a significant amount of MICG synthesis, while only a trace of MICG synthesis was atrributable to B-cells.