Autoreactive antibody-forming cells directed against thymocytes and thymus-derived lymphocytes.

Antibody-forming cells with specificities against syngeneic and allogeneic thymocytes are detected in the spleens of normal mice after activation in vitro or in vivo with lipopolysaccharide (LPS). The activity of such cells was measured in a complement-dependent plaque assay employing trypan blue dye to assess zones of lysis. Plaques were rarely seen in the absence of LPS treatment. Anti-immunoglobulin added to the plaque assay abrogated the appearance of plaques, but the addition of LPS had no effect. Furthermore, plaque formation was 2-mercaptoethanol sensitive indicating that the antibody responsible was of the IgM class. Plaque forming cells (PFC) were also detected against syngeneic and allogeneic lymph node cells and to a much lesser extent against splenocytes. The numbers of PFC found against syngeneic, allogeneic, or a mixture of thymocytes was similar and ranged from 1000 to 3000 PFC/10(8) viable spleen cells tested. All murine strains tested, including congenitally athymic nude mice, exhibited anti-thymocyte PFC after LPS activation. C3H/HeJ mice, genetically unresponsive to LPS, did not respond mitogenically to LPS and no anti-thymocyte plaques were observed. These findings suggest that clones of autoreactive B cells are present in normal mice and can be activated by LPS.     

Studies on column fractionation of immune cells. VI. Separation of thymus-derived lymphocytes by means of protein beads coated with antigen-antibody complexes.

Calf serum beads coated with antigen-antibody complexes were used as cellular immuno-adsorbents to separate mouse T-lymphocytes with a purity of more than 90%. The beads coated by means of glutaraldehyde could be used at least three times without loss of cell-binding capacity.     

Generation of thymus-derived helper cells by macrophage-associated antigen

A double cell transfer system was used to investigate the efficacy of macrophage bound antigen in generating carrier-reactive helper T cells. Macrophage bound antigen was found to be three orders of magnitude more potent than soluble antigen in T cell priming. The results are discussed with reference to the involvement of macrophages or related cells in the normal processes of immune induction.     

Genetically modified immune cells for cancer immunotherapy

正Cancer immunotherapy refers to harnessing the body’s immune system to fight cancer. Cancer immunotherapy has been the hotspot for oncotherapy research since the late 19th century when Dr. Williams Coley used mixed bacteria to boost the body’s immune response to fight cancer. With the rapid development of biotechnology and an increase in the understanding of the body’s immune system, cancer immunotherapy has attracted increased research focus because of its benefits in cancer patients and is considered a leading breakthrough since 2013.     

Nonspecific cytotoxicity of spleen cells and the specific cytotoxic action of thymus-derived lymphocytes in vitro

Spleen cells removed from immunized mice specifically kill allogeneic lymphoma cells in vitro, but in the presence of specific antigen nonspecific target cell growth inhibition also occurs. Only the specific target cell killing was found to be θ-sensitive, the nonspecific cytotoxicity was caused by a population of θ-resistant, adherent, and AMS-sensitive cells. Nonspecific cytotoxic effects were caused by spleen cells from normal mice after incubation with endotoxin, and these effects were inhibited by removal of the adherent cells.     

Importance of thymus-derived lymphocytes in cell-mediated immunity to infection

Peripheral blood lymphocytes from ten human neonates and ten adults were studied. Many more medium and large cells were identified in neonates, and the ultrastructure of the medium-sized lymphocytes resembled guinea pig transitional cells. There were 20 times more nucleoside-incorporating lymphocytes in the newborn samples, and a neonatal high-labeling cell was identified.     

Specific immune recognition of autologous tumor by lymphocytes infiltrating colon carcinomas: Analysis by cytokine secretion

Summary Tumor-infiltrating lymphocytes (TIL) were grown in the presence of interleukin-2 from 19 colon carcinoma specimens, including 1 primary lesion and 18 metastatic lesions. These cultures showed a median proliferation of 606-fold (range 13-fold to 28 000-fold) over 49 culture days (range 26–76 days). By phenotype, mature cultures were 69%–99% CD3⁺ (mean 93%) and contained mixed populations of CD4⁺ and CD8⁺ cells (CD4>CD8 in 10 of 19 cultures). Fresh cryopreserved colon tumors were not lysed by autologous TIL in short-term⁵¹Cr-release assays, and were poorly lysed by lymphokine-activated killer cells. Ten TIL cultures were assayed for cytokine secretion in response to autologous and allogeneic tumors during a 6- to 24-h coincubation. Culture supernatants were tested by ELISA for the presence of granulocyte/macrophage-colony-stimulating factor, interferon , and tumor necrosis factor . Of 10 TIL, 4 secreted at least two of these cytokines specifically in response to autologous and/or HLA-matched fresh allogeneic colon carcinomas, but not to melanomas or HLA-unmatched colon carcinomas. Cytokine secretion was mediated by both CD4⁺ and CD8⁺ TIL, and could be inhibited by mAb directed against the appropriate class of MHC antigen. These data provide evidence for specific, MHC-restricted immune recognition of human colon carcinomas by T lymphocytes.     

Pretreatment of P815 mastocytoma cells with inhibitors of protein synthesis reduces their susceptibility to lysis by cytotoxic thymus-derived lymphocytes

Protein synthesis inhibitors like cycloheximide, emetine, and puromycin diminish the ability of P815, a mastocytoma of DBA/2 mice, to react with anti-H-2^d cytotoxic thymus-derived lymphocytes (CTLs). Compared to untreated P815, tumor cells incubated with the protein synthesis inhibitors exhibited a reduced sensitivity to lysis and a reduced ability to inhibit lysis of untreated P815 cells. Consistent with this reduced reactivity of cycloheximide-treated P815 cells with CTLs was the inability of anti-H-2^d CTLs to form T cell-target cell conjugates with treated P815 cells. As evaluated by the binding of an anti-H-2^d serum, treated P815 cells expressed the same amount of H-2 membrane antigen as untreated cells. However, treated cells were still lysed by CTLs in the presence of the agglutinator, concanavalin A (Con A).     

Role of thymus-derived lymphocytes in acquired immunity to salmonellosis in mice

The relative role of thymus-derived (T-) lymphocytes and bone marrow-derived (B-) cells in acquired immunity to salmonellosis was examined in mice. The results demonstrate that the protective capacity of the donor immunized mice could be passively transferred to the recipient mice by spleen cells but not with peritoneal exudate cells or sera. A high cell number of spleen cells (2 X 10(8)/mouse) were required before passive transfer of immunity could be obtained. Of the T-lymphocytes and B-cell populations of spleen cells, T-cells from immune mice were effective in conferring protection to the recipient mice.     

Surface proteins of thymus-derived lymphocytes and bone-marrow-derived lymphocytes. Selective isolation of immunoglobulin and the θ-antigen by non-ionic detergents

Accessible surface proteins of thymus-derived lymphocytes (T-cells) of normal CBA mice and bone-marrow-derived lymphocytes (B-cells) of congenitally athymic nu/nu mice were analysed. The surfaces of lymphocytes were radioiodinated by using the enzyme lactoperoxidase (EC 1.11.1.7), then solubilized either in acid-urea or in the non-ionic detergent Nonidet P-40. These lysates were then precipitated with antisera specific to either immunoglobulin or the theta-alloantigen in order to assess the presence of these surface markers. Comparable amounts of radioactivity in proteins specifically precipitable as immunoglobulin were obtained from T-lymphocytes and B-lymphocytes when the cells were disrupted by acid-urea. This immunoglobulin had mol. wt. approx. 180000 and was composed of light chains and mu-type heavy chains. When radioiodinated lymphocytes were solubilized with Nonidet P-40, 3-4% of radioiodinated high-molecular-weight protein of B-cells consisted of immunoglobulin, a result similar to that found with acid-urea extraction. However, with the detergent extraction, only 0.1% of T-cell surface protein was precipitable by anti-globulin reagents. The theta-alloantigen was isolated from CBA T-cells both by acid-urea and by detergent lysis. This protein possessed a mobility on polyacrylamide-gel electrophoresis in sodium dodecyl sulphate which was consistent with a mol. wt. of 60000. An identical component was isolated from the theta-positive thymoma WEHI 105. The theta-antigen was not isolated from B-cells by either of the extraction procedures used. These results provide further evidence that the surface membranes of normal T-cells and B-cells differ in physicochemical properties. In particular, various surface components possess differential solubilities in non-ionic or organic solvents. This observation provides an explanation for discrepant results that have appeared in the literature concerning the isolation of immunoglobulin from T-lymphocytes.     

Enhanced recognition of a modified peptide antigen by cytotoxic T cells specific for influenza nucleoprotein

A previously identified Kd restricted epitope of influenza A virus nucleoprotein (147-161) was modified, resulting in recognition by Kd restricted cytotoxic T cells at significantly lower concentrations than the natural peptide sequence. This was achieved by first refining the epitope to the minimum determinant 147-158. Deletion of arginine 156 resulted in a peptide that was shown to be greatly superior in both dose response titrations and in its rate of association with cells to form targets. Analog peptides were tested to determine the important amino acid changes. These data suggest that T cell epitopes can be modified to result in improved immunological recognition.     

Preventive effect of hapten-reactive thymus-derived helper lymphocytes on the tolerance induction in hapten-specific precursors of antibody-forming cells.

The role(s) of helper T lymphocytes in preventing or altering tolerance induction in DNP-specific B lymphocytes was studied. As DNP-reactive helper T cells were reactive against the DNP-portion of the DNP-D-GL molecule, we could probe definitively the physiological role of helper T cells in preventing tolerance induction in B lymphocytes by DNP-D-GL. The results demonstrated that the induction of DNP-specific B cell tolerance by DNP-D-GL can be completely prevented by the presence of DNP-reactive helper T cells, and provide evidence that one critical role of helper T cell participation in humoral responses to antigens is to circumvent the development of a tolerogenic signal that, in the absence of such T cell function, might otherwise ensue after binding of the antigenic determinants by specific B lymphocytes.     

Rotavirus-specific protein synthesis is not necessary for recognition of infected cells by virus-specific cytotoxic T lymphocytes.

We found that rotavirus-specific protein synthesis was not necessary for recognition by virus-specific cytotoxic T lymphocytes (CTLs). In addition, CTLs lysed rotavirus-infected target cells prior to production of infectious virus. Target cell processing of rotavirus antigens for presentation to CTLs was enhanced by treatment of rotavirus with trypsin prior to infection; trypsin-induced cleavage of the viral hemagglutinin (vp4) has previously been found to facilitate rotavirus entry into target cells by direct penetration of virions through the plasma membrane. We conclude that sufficient quantities of exogenous viral proteins may be introduced into the cytoplasm for processing by target cells. The mechanism by which rotavirus proteins are processed for presentation to the target cell surface remains to be determined.     

Effects of thermal stress on tumor antigenicity and recognition by immune effector cells

The primary rationale for the application of clinical hyperthermia in the therapy of cancer is based on the direct cytotoxic effect of heat and the radio-chemosensitization of tumor cells. More recently, additional attention is given to the observation that heat and heat-shock proteins can activate the host’s immune system. The expression of heat-shock genes and proteins provides an adaptive mechanism for stress tolerance, allowing cells to survive non-physiologic conditions. However, the same adaptive mechanism can ultimately favor malignant transformation by interfering with pathways that regulate cell growth and apoptosis. Cytoprotection and thermotolerance raised the concern that heat-treated tumor cells might also be resistant to attack by immune effector mechanisms. Many studies, including those from our group, address this concern and document that heat-exposure, although transiently modulating sensitivity to CTL, do not hinder CTL attack. Moreover, there are promising reports of heat-related upregulation of NK-activating ligands, rendering those tumors which have lost MHC class I molecules target for NK cell attack. Heat-induced cytoprotection, therefore, does not necessarily extend protection from cytotoxic immune mechanisms. When interpreting the effects of heat, it is important to keep in mind that thermal effects on cell physiology are strongly dependent on the thermal dose, which is a function of the magnitude of change in temperature and the duration of heat exposure. The thermal dose required to induce cell death in vitro strongly varies from cell type to cell type and depends on microenvironmental factors (Dewey 1994). Therefore, to dissect the immunological behaviour of a given tumor and its micro-environment at different thermal doses, it is essential to characterize the thermosensitivity of every single tumor type and assess the proportion of cells surviving a given heat treatment. In this review, we summarize the pleiotropic effects that heat exposure has on tumor cells. In particular, we focus on the effects of heat on the antigen presentation of tumor cells and their susceptibility to immune effector mechanisms. We emphasize that the response to thermal stress is not a one-time point event, but rather a time period starting with the heat exposure and extending over several days of recovery. In addition, the response of tumor cells and their susceptibility to immune effector cells is strongly dependent on the model system, on the magnitude and duration of the thermal stress and on the time of recovery after heat exposure. Consideration of these aspects might help to explain some of the conflicting results that are reported in the field of thermal stress response. This article forms part of the Symposium in Writing "Thermal stress-related modulation of tumor cell physiology and immune responses", edited by Elfriede Noessner.