Specific pancreatic beta-cell surface antigens recognized by a xenogenic antiserum

An antiserum (R4) from a rabbit immunized with suspensions of C57BL/61 ob/ob mouse islet cells contains antibodies which in a 125I-protein A radioligand assay can be demonstrated to bind to single cell suspensions of normal Naval Medical Research Institute (NMRI) mouse islet cells. The binding of 125I-protein A to islet cells was about four times that of normal rabbit serum (NRS) after incubation at a 1/600 dilution of R4 antiserum quantitatively absorbed to mouse spleen lymphocytes (R4A antiserum) and hepatocytes. Subsequent absorption of the R4A antiserum to islet cells significantly reduced the binding of 125I-protein A to islet cells incubated with the doubly absorbed serum. Immunoprecipitation of radiolabeled islet cell lysates followed by SDS polyacrylamide gel electrophoresis and autoradiography suggested that the R4A antiserum recognized a Mr 40,000 glycoprotein. This glycoprotein was not detected in spleen lymphocytes. Electron microscope detection of gold-protein A complexes suggested that the binding of islet cell surface antibodies was cell specific. islet cell suspensions incubated with R4A antiserum and gold-protein A showed that 86 +/- 3 gold particles were bound per 100 beta-cells (mean +/- SE for six experiments). In contrast, the number of gold particles per 100 endocrine non-beta-cells was 8 +/- 1 which was similar to the number achieved with NRS (3 +/- 1) on all endocrine islet cells. Our observations suggest that the pancreatic islet cells, in particular the beta-cells, express a specific antigen.     

The effects of cortisol on the primary response of mouse spleen cell cultures to heterologous erythrocytes

Cell viability and the production of direct PFC were studied in mouse spleen cell cultures after cortisol treatment in vivo or in vitro at various times relative to primary stimulation with SRBC in vitro.Cortisol treatment in vivo reduced spleen cell numbers by 88% after 48 hr, but cultures of the remaining cells produced as many PFC in vitro as did cultures of equal numbers of normal spleen cells.In normal spleen cell cultures incubated with cortisol for 4 hr prior to the addition of antigen, peak responses of PFC/culture and PFC/10⁶ cells occurred 24 hr later than in controls and averaged, respectively, 27% and 141% of control values. Minimum viable cell numbers were observed in cortisol-treated cultures after 3 days; thereafter cell numbers gradually increased. These results were not significantly altered when cultures were treated simultaneously with cortisol and antigen.The response was not suppressed if the addition of antigen preceded that of cortisol by more than 4 hr. Suppression was also considerably reduced if fetal calf serum was used when preparing cells for culture.     

Effect of media conditioned by concanavalin A activated spleen cells on pancreatic islet cells

The effect of media conditioned by concanavalin A-activated spleen cells (C-sup) on insulin release and its islet cell cytotoxicity were studied. In a functional study, C-sup significantly inhibited both basal insulin release and glucose-stimulated insulin release. Morphologically, C-sup had a destructive effect on isolated islets after 72 h incubation. Islet cell cytotoxicity was shown by lactate dehydrogenase (LDH) release assay after 5 days incubation with C-sup in a dose-dependent manner. These results suggest that acceleration of the onset of diabetes in young diabetes prone (DP) Bio-Breeding/Worcester (BB/W) rats following the injection of C-sup may depend on the suppressive and cytotoxic effects of C-sup on pancreatic islet cells.     

The proliferative response of the spleen in cryosurgery.

Using ³H-thymidine autordiography, we studied the cellular proliferation of the spleen of rats after cryolesions in liver, kidney, spleen, and stomach.In the germinal centers at first, a dissociation develops, followed by a hyperplasia with high labeling indices of the germinal center cells with a maximum between the second and third postoperative day. In the surrounding lymphatic mantle zone of the white pulp, as well as in the marginal zone, an increased labeling index of the cells can be observed between the first and second day. The highest percentages of labeled cells in the red pulp are seen on the fifth postoperative day.These cell kinetic results correspond very well with those after antigenic stimulation, for instance, after intravenous injection of sheep erythrocytes. Therefore, these findings suggest that an immunologic reaction occurs in the spleen after cryolesions on parenchymal organs.     

Natural killer cell activity in the rat. V. The circulation patterns and tissue localization of peripheral blood large granular lymphocytes (LGL)

Large granular lymphocytes (LGL) and T cells were separated from blood by centrifugation on discontinuous gradients of Percoll, were labeled with [3H]uridine or [111In]oxine, and were injected i.v. into syngeneic euthymic or athymic nude rats. The tissue distribution of these labeled cells was monitored for up to 24 hr after transfer by scintillation counting of tissue homogenates and autoradiography of tissue sections. In normal euthymic rats, the main sites of LGL localization were the alveolar walls of the lungs and spleen red pulp; however, they were not detectable in the major traffic areas of T lymphocyte recirculation, the spleen white pulp, and lymph nodes. Furthermore, the density of labeled LGL was very low in the small intestine, thymus, kidney, and liver, although on a per-organ basis, about 10% of the injected radioactivity was found in the liver by 24 hr post-injection. When 111In-labeled LGL were injected i.v. into rats with an indwelling thoracic duct cannula, they completely failed to enter the thoracic duct lymphocyte (TDL) population over an observation period of 6 days. This finding was markedly different from the results obtained with T cells and was consistent with the lack of natural killer and antibody-dependent cellular cytotoxicity activity observed among TDL, even in rats pretreated with the biological response modifier, poly I:C. LGL in athymic nude rats also failed to recirculate between blood and lymph. However, in contrast to normal euthymic animals, a significant increase in the localization of radiolabeled LGL to lymph nodes was observed in nude rats between 30 min and 24 hr. Taken as a whole, these findings define the areas within the lungs and spleen in which blood LGL normally localize, and clearly demonstrate that LGL do not normally recirculate between blood and lymph.     

Heterologous antibody responses in mice with chronic T. cruzi infection: depressed T helper function restored with supernatants containing interleukin 2

Antibody production to sheep erythrocytes (SRBC) or hapten-conjugated SRBC (TNP-SRBC) was studied in mice with chronic Trypanosoma cruzi infections. Studies in vivo demonstrated that both IgM and IgG anti-SRBC responses were suppressed during chronic infection. Secondary IgG responses were suppressed regardless of whether the primary immunization was given before or after infection. The ability of cells from infected mice to provide help for antibody production was examined in vitro. Anti-SRBC responses were restored to cultures of whole spleen cells from infected mice by the addition of interleukin 2 (IL 2)-rich supernatants, indicating that these cells were capable of antibody production when sufficient help was provided. T cells from SRBC-primed infected mice were unable to provide significant help to normal B cell/M phi cultures for in vitro anti-TNP or anti-SRBC responses. The percentages of Thy-1+, Lyt-1+, and Lyt-2+ spleen cells were not significantly different between normal and infected mice. Anti-TNP and anti-SRBC responses were restored to cultures that contained T cells from infected mice and normal B cell/M phi by the addition of IL 2-rich spleen cell supernatants. The suppression of in vitro antibody responses in mice with chronic T. cruzi infections was associated with a lack of T cell help, which was provided by exogenous spleen cell supernatant.     

In Vitro Reconstitution of Anti-Sheep Erythrocyte Antibody Response of T Cell-Depleted Spleen Cells by Allogeneic T Cells or by Factors Derived from Them

Restoration of the impaired antibody response to sheep erythrocytes (SRBC) in cultures of mouse spleen cells, which were deprived of thymus-derived lymphocytes (T cells) by treatment with anti-mouse brain-associated θ (BAθ) antiserum and complement, was studied by adding a small portion of syngeneic or allogeneic normal spleen cells in vitro. Allogeneic spleen cells had a far greater effect than syngeneic spleen cells on the restoration, as far as the normal spleen cells added were able to recognize the alloantigens on the anti-BAθ serum-treated spleen cells (bone marrow-derived lymphocytes). Treatment of the allogeneic spleen cells with mitomycin C did not affect their activity in the restoration of the impaired antibody response. The possibility that the role of T cells in the antibody response to SRBC may be replaced by a nonspecific mediator derived from T cells reacting with allogeneic cells was proven by the finding that supernatant of the mixed allogeneic spleen cell cultures restored the impaired anti-SRBC antibody response of the T cell-depleted spleen cells. The effect of such culture supernatant on the restoration of the antibody response was greatest when it was added to the T cell-depleted spleen cell cultures one day after cultivation with SRBC, suggesting that the effectiveness may result from triggering of the proliferation and differentiation of antibody-forming cell precursors, which have already reacted with the antigen, to antibody-forming cells.     

Antigen transport II. The significance of the localization of antigen-laden cells in the spleen

Previous studies have demonstrated that macrophage-like cells transporting antigen, e.g., human serum albumin (HSA) appear in thoracic duct lymph and blood shortly after antigen injection. The in vivo migration of these antigen-laden (Ag-L) cells from the blood stream was examined systematically by transferring Ag-L cells bearing ¹²⁵I-labelled HSA into syngeneic rats. There was no evidence autoradiographically that Ag-L cells migrated into lymph nodes, but the localization in the spleen followed a defined pattern: within the first hours after transfer, a majority of radiolabelled cells were identified in the marginal zone; by 3 hr and up to 4 days later, 60–80% of labelled cells were resident in the red pulp; Ag-L cells failed to migrate into the white pulp in significant numbers. Ag-L cells which had localized to the spleen, when examined 3 and 18 hr after transfer using combined autoradiography and immunoperoxidase staining, did not express la determinants in situ. The ability of Ag-L cells to stimulate an adoptive secondary response was tested in splenectomized, irradiated recipients receiving HSA-specific memory cells. Removal of the spleen before transfer severely reduced the antibody response evoked by Ag-L cells transporting HSA, thus indicating the functional importance of antigen transport to the spleen. Since Ag-L cell migration was primarily into the red pulp, we have considered whether the red pulp may provide a relevant microenvironment for lymphocyte/ antigen interaction.     

Protein A-binding immunosuppressive mouse serum factors

Summary In this study protein A of Staphylococcus aureus has been used to isolate an immunosuppressive component present in mouse serum. The suppressive effect of mouse serum on lymphocyte activation was partially abrogated by prior adsorption on protein A, and also by ammonium sulfate precipitation or specific immune precipitation with anti-IgG but not with anti-IgM. Protein A-binding material was isolated after chromatography on protein A-Sepharose and studied in spleen cell cultures. Protein A eluates from normal or NZB/NZW mice were found to suppress concanavalin A (Con A)-activated normal mouse spleen cells, and suppression was more potent with NZB/NZW serum isolates. Suppressive activity was dependent upon the dose of eluate added to cell cultures. The suppressive effect of NZB/NZW protein A-binding material was apparent in both Con A- and lipopolysaccharide (LPS)-stimulated normal mouse spleen cells, and required early addition to the cell cultures or preincubation with target lymphocytes. The suppressive activity was not detectably cytotoxic during a suppressive preincubation period. The possible relevance of these observations to experimental strategies in tumor immunotherapy is discussed.     

Immunohistochemical analysis of splenic tissue in rats with destruction of the hypothalamic structures

The immunoenzyme histochemical technique to stain the IgM- and IgD-bearing cells was used to study the morphometric characteristics of B-lymphocyte-dependent zones in spleen white pulp of Wistar rats (intact, sham operated and after cortex or hypothalamic lesions). In the groups of sham-operated and cortex-lesioned rats it has been shown the increase of spleen weight 7 days after the operation due to the increase of the red pulp weight. The white pulp compartment's ratio is not affected. Lesioning of the posterior hypothalamic area prevents these effects of the operation, while local coagulation of the lateral hypothalamic area causes a significant decrease of the weight of spleen primary follicules which contain IgM+IgD+-bearing B-lymphocytes exerting characteristics of circulating pool of B-lymphocytes. These data are in favour of the CNS participation in regulation of B-lymphocyte migratory activity.     

Depressed Cellular Formation of Antibody to Shigella Antigens In Vitro by Spleen Cell Cultures from Unresponsive Mice

Specific antibody plaque-forming cells (PFC) to Shigella-soluble antigen did not appear in spleen cell cultures from Shigella-tolerant mice, as occurred with similar cultures prepared from normal mice immunized with Shigella antigen prior to sacrifice. Cultures from tolerant mice also failed to form serologically detectable amounts of agglutinins in vitro. Exposure of cell cultures from tolerant mice in vitro to additional antigen had little or no effect on appearance of plaque-forming cells to Shigella. Spleen cells from normal control mice formed readily detectable levels of antibody, as well as specific antibody plaque-forming cells, after similar stimulation with antigen either in vivo or in vitro. The absence of antibody-forming cells in cultures prepared from spleens of tolerant mice was specific since such cultures, as well as those from normal control mice, formed numerous antibody plaques to unsensitized sheep erythrocytes in vitro after in vivo challenge of the mice with sheep erythrocytes. Tolerance to Shigella antigen, as assessed by absence of antibody-forming cells in vitro, persisted for several months. Spleen cell cultures from tolerant mice less than 3 to 4 months of age did not form significant numbers of antibody plaques, even after in vitro exposure to specific antigen. However, spleen cultures prepared from neonatally treated mice, approximately 6 to 8 months old, formed essentially normal numbers of specific PFC in vitro, indicating that the animals had "recovered" from tolerance and that their lymphoid cells were capable of responding to Shigella antigen in vitro. Absence of specific PFC in cell cultures from tolerant animals supports the concept that tolerance is due to a central failure of specific immunocompetent cells and not due to an inhibitory effect caused by either "excess" antigen or humoral antibody.     

Adoptive transfer of experimental allergic encephalomyelitis: requirement for macrophages in activation of spleen cells in vitro by concanavalin A or myelin basic protein

Adoptive transfer of experimental allergic encephalomyelitis (EAE) in Lewis rats is markedly enhanced when sensitized spleen cells are incubated in vitro with either concanavalin A (Con A) or myelin basic protein (MBP). This phenomenon permits more detailed analysis of the inductive phase of EAE than has heretofore been possible. We have now demonstrated that macrophages are essential for the process to occur, and that they probably act by different means depending on whether activation is carried out with the mitogen or the specific antigen. Depletion of macrophages by passage through G-10 Sephadex columns prevented activation of spleen cells by either Con A or MBP. The effect of Con A could be partially restored with 2-mercaptoethanol, while activation by MBP could not. Reconstitution of macrophage-depleted cultures with peritoneal exudate cells from either immune or normal rats fully restored activation by both Con A and MBP. Supernatants taken from spleen cell cultures were unable to restore the transfer activity of macrophage-depleted cells, indicating that activation probably is not mediated by a soluble factor released by macrophages. Depletion of macrophages after incubation with Con A slightly reduced transfer activity, but depletion after incubation with MBP abolished it. Thus the mechanisms of activation appear to differ in the two systems, and in the case of MBP the macrophage-mediated portion of the process may be incomplete prior to adoptive transfer.     

Effects of lymphocytes from Marek's disease-infected chickens on mitogen responses of syngeneic normal chicken spleen cells.

PHA responses have been measured in lymphoid cell cultures prepared by mixing normal chicken spleen cells with spleen or thymus cells from syngeneic chickens infected with the oncogenic herpesvirus MDV. Results of these studies may be summarized as follows: 1) spleen cells from MDV-infected chickens with visceral lymphomas inhibit the PHA response of normal spleen cells possibly by release of soluble inhibitory factors in response to the mitogen; 2) lymphoid cells from asymptomatic MDV-infected chickens, although hyporeactive themselves to PHA, can have a stimulatory effect on PHA responses of normal spleen cells in mixed cultures; 3) spleen cells from MDV-infected chickens, effectively protected from viral oncogenesis by HVT vaccination, show normal reactivity to PHA in spearate cultures and may react in mixed cultures like normal lymphocytes, with neither a pronounced stimulatory nor inhibitory effect on the PHA response of normal spleen cells.     

Long-term cryopreservation of reaggregated pancreatic islets resulting in successful transplantation in rats

Preservation of pancreatic islets for long-term storage of islets used for transplantation or research has long been a goal. Unfortunately, few studies on long-term islet cryopreservation (1 month and longer) have reported positive outcomes in terms of islet yield, survival and function. In general, single cells have been shown to tolerate the cryopreservation procedure better than tissues/multicellular structures like islets. Thus, we optimized a method to cryopreserve single islet cells and, after thawing, reaggregated them into islet spheroids. Cryopreserved (CP) single human islet cells formed spheroids efficiently within 3–5 days after thawing. Approximately 79% of islet cells were recovered following the single-cell cryopreservation protocol. Viability after long-term cryopreservation (4 weeks or more) was significantly higher in the CP islet cell spheroids (97.4 ± 0.4%) compared to CP native islets (14.6 ± 0.4%). Moreover, CP islet cell spheroids had excellent viability even after weeks in culture (88.5 ± 1.6%). Metabolic activity was 4–5 times higher in CP islet cell spheroids than CP native islets at 24 and 48 h after thawing. Diabetic rats transplanted with CP islet cell spheroids were normoglycemic for 10 months, identical to diabetic rats transplanted with fresh islets. However, the animals receiving fresh islets required a higher volume of transplanted tissue to achieve normoglycemia compared to those transplanted with CP islet cell spheroids. By cryopreserving single cells instead of intact islets, we achieved highly viable and functional islets after thawing that required lower tissue volumes to reverse diabetes in rats.     

Optimization of condition(s) towards establishment of primary islet cell cultures from WNIN/Ob mutant rat

WNIN/Ob, a mutant rat strain, developed at the National Center for Laboratory Animal Sciences (NCLAS) facility of National Institute of Nutrition (NIN), is a new animal model to study the metabolic syndrome. These animals have 47% fat in their body and isolation of islets from these animals were compounded due to the formation of amorphous viscous and jelly like material which reduced the islet yield. However, islets isolated from WNIN adult (≥12 months) control rats gave a good islet recovery, under standard isolation procedures using collagenase digestion. In the present study we optimized culture conditions in WNIN/Ob rats to isolate islets with higher yield, and also established primary islet cell cultures from these mutant rats, retaining cellular integrity and functionality.     

Duodenal-jejunal bypass protects GK rats from {beta}-cell loss and aggravation of hyperglycemia and increases enteroendocrine cells coexpressing GIP and GLP-1

Dramatic improvement of type 2 diabetes is commonly observed after bariatric surgery. However, the mechanisms behind the alterations in glucose homeostasis are still elusive. We examined the effect of duodenal-jejunal bypass (DJB), which maintains the gastric volume intact while bypassing the entire duodenum and the proximal jejunum, on glycemic control, β-cell mass, islet morphology, and changes in enteroendocrine cell populations in nonobese diabetic Goto-Kakizaki (GK) rats and nondiabetic control Wistar rats. We performed DJB or sham surgery in GK and Wistar rats. Blood glucose levels and glucose tolerance were monitored, and the plasma insulin, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) levels were measured. β-Cell area, islet fibrosis, intestinal morphology, and the density of enteroendocrine cells expressing GLP-1 and/or GIP were quantified. Improved postprandial glycemia was observed from 3 mo after DJB in diabetic GK rats, persisting until 12 mo after surgery. Compared with the sham-GK rats, the DJB-GK rats had an increased β-cell area and a decreased islet fibrosis, increased insulin secretion with increased GLP-1 secretion in response to a mixed meal, and an increased population of cells coexpressing GIP and GLP-1 in the jejunum anastomosed to the stomach. In contrast, DJB impaired glucose tolerance in nondiabetic Wistar rats. In conclusion, although DJB worsens glucose homeostasis in normal nondiabetic Wistar rats, it can prevent long-term aggravation of glucose homeostasis in diabetic GK rats in association with changes in intestinal enteroendocrine cell populations, increased GLP-1 production, and reduced β-cell deterioration.     

Prevention of transplantable tumors by adoptive transfer of spleen cells from immunized rats.

Fischer 344 rats were specifically hyperimmunized with allogeneic, nonvirus-producing [Kirsten murine sarcoma virus (KiMSV)] or syngeneic, virus-producing [KiMSV (Rasheed)] rat tumors. Spleen cells taken from these rats adoptively transferred protection against a 100 to 1,000 X rat tumor dose50 cell challenge with several different transplantable rat tumors. Protection was obtained with spleen cells after removal of adherent cells and macrophages but not peritoneal cells. The spleen cells were not directly cytotoxic but required more than 3 days residence in the recipient before protecting the recipient against challenge. No protection against tumor cell challenge was observed when spleen cells were lethally x-ray irradiated before injection into nontreated rats. Spleen cells taken from rats immunized with normal histocompatibility antigens did not protect in this test system.     

Immune parameters of untrained or exercise-trained rats after exhaustive exercise

The effect of a single exhaustive swimming exercise bout on immune competence of untrained or exercise-trained female Wistar rats was compared with the competence of control sedentary rats. After the exhaustive exercise bout, the blastogenic response to concanavalin A by spleen cells of untrained rats was extensively suppressed, whereas the response of the trained rats was only marginally suppressed. The suppressed immune competence of the untrained rats after the exhaustive exercise was associated with an increase in immune-suppressive activity of splenic lymphocytes. The macrophages of the untrained rats and of the control sedentary rats were slightly immune suppressive to normal spleen cells through a prostaglandin-dependent mechanism. The addition of prostaglandin E2 (PGE2) to the blastogenesis cultures revealed that the spleen cells of untrained rats were unusually sensitive to the suppressive effects of PGE2. In contrast to the untrained rats, the marginal level of immune suppression in trained rats after the exhaustive exercise was associated with a lesser degree of lymphocyte-suppressive activity, an immune stimulatory activity by the splenic macrophages, and an insensitivity of the splenic lymphocytes to the suppressive effects of PGE2.