Infection by human cytomegalovirus and rubella virus of cultured human fetal islets of Langerhans

Several viruses are implicated in the pathogenesis of pancreatic beta cell destruction and the onset of insulin-dependent (type 1) diabetes mellitus (IDDM). However, it is still controversial as to whether viral infection can exert direct cytopathic effects on beta cells. We have studied the effect of infection by human cytomegalovirus (CMV) and rubella virus on human fetal pancreatic islets in tissue culture. Although morphological changes were observed in CMV-inoculated islet cells, such infection did not lead to changes in levels of secreted immunoreactive insulin. On the other hand, infection by rubella virus did lead to significantly lower levels of immunoreactive insulin in the absence of demonstrable cytopathic effect. These results indicate that viral infection of human pancreatic islet tissue can occur as demonstrated through tissue culture techniques, and that such infection leads to changes in levels of secreted insulin in some cases but not others.

The effects of polyinosinic:polycytidylic acid on the graft-versus-host reaction. III: Increased severity of the reaction with delayed pI:C treatment

We have been investigating the effects of polyinosinic:polycytidylic acid (pI:C), an interferon inducer, on the graft-versus-host reaction. We have previously shown that pI:C treatment of C57BL/6xAF1 (B6AF1) recipient mice immediately before injection of C57BL/6 (B6) parental lymphocytes inhibited the immuno-suppression and pathological changes normally caused by the GVH reaction, by a mechanism apparently identical to that seen in F1 hybrid resistance (HR) to hematopoietic grafts. We now demonstrate that delaying pI:C treatment by as little as 48 hr produces the opposite effect. Treatment of recipient B6AF1 mice at different days after transfer of parental lymphocytes induced a marked increase in the severity of the GVH reaction, as measured by a decreased plaque-forming cell response to sheep erythrocytes; decreased proliferative response to the T and B cell mitogens PHA, Con A, and LPS; increased pathological changes in both lymphoid and nonlymphoid tissues; and increased GVH-associated mortality. This effect is unrelated to HR, as pI:C was able to augment the severity of the GVH reaction when A strain cells were injected into AxCBAF1 recipients, which do not manifest HR. Early pI:C treatment (1 and 2 days after parental cell transfer) increased the severity of the GVH reaction much more than later pI:C treatment (7 and 8 days after parental cell transfer). This observation, along with the demonstration of altered pathology in GVH mice treated with pI:C, suggests that the effect of pI:C is not mediated through a direct suppressive effect of IF on the cells responding in either the PFC or mitogen assays, but rather by the ability of IF to activate or suppress mechanisms involved in the development of GVH-induced alterations.

The effect of islet-activating protein (IAP) of pertussis toxin on the spontaneous diabetic syndrome in the rat

The administration of the Islet-Activating Protein (IAP) of pertussis toxin results in an increased insulin response to oral glucose in a dose- dependent manner. This response can be detected for up to 12 days after a single injection. In addition, IAP increases the number of peripheral blood leucocytes and lymphocytes. Inbred strains of rats differ in the magnitude of the leucocyte but not the insulin responses to IAP. Multiple injections of 1,000 ng of IAP to diabetes-prone BB rats at 50, 64 and 78 days of age caused an increased release in response to glucose challenge and a slight increase in peripheral blood leucocytes when compared to animals receiving saline injections. The prevalence of insulin-dependent diabetes in BB rats was increased in the IAP group as compared to controls. Histolgic examination of the pancreas at the time of detection of diabetes revealed a widespread intense insulitis. We speculate that the increased expression of disease observed in the BB rats receiving IAP may be secondary to the chronic increase in insulin release and/or to an effect on the cells of the immune system.

Molecular mechanisms of oncogenesis

Cellular oncogenes (c-oncs) have been highly conserved throughout evolution and subserve important roles in growth and development. Both in development and the neoplastic state, c-oncs appear to collaborate rather than function independently. Cellular oncogenes are activated in the neoplastic process by four (nonviral) mechanisms; (a) chromosomal translocations; (b) gene amplifications; (c) point mutations; and (d) DNA rearrangements. The timing of c-onc gene product expression may be as important in oncogenesis as the level of expression. At this writing, mutant oncogenes have not been shown to be inherited. Oncogene amplification, if important in oncogenesis, is more likely to be involved with tumor progression rather than initiation. Chromosomal/molecular aberrations tend to be characteristic for a given type of cancer. These genetic alterations are often situated near heritable fragile sites, tumor-suppressor gene loci and/or oncogene loci. Similar molecular mechanisms involving translocations and inversions may underly the common T and B cell neoplasms. The loss/inactivation of both normal alleles at a locus thought to encode for tumor-suppressing activities (antioncogenes) may represent an event common to many childhood and adult neoplasms. The consistency and cell specificity with which this has been identified is consistent with a role for such genes in cellular differentiation. At this writing, the paradigm for such a controlling locus is 13q14, the site of the retinoblastoma gene. Based on recent studies in familial and sporadic Wilms' tumor which suggest etiological heterogeneity, theoretical modifications of the carcinogenesis model which has been central to understanding retinoblastoma may soon be forthcoming to explain molecular mechanisms operative in other cancer. The role of genomic imprinting in carcinogenesis is only recently being explored. Further study of this process may prove to be a fruitful area of future research.

Metabolic time course and immunologic concomitants of adoptive transfer of type I diabetes in the BB rat

The metabolic and cellular immune changes during adoptive transfer of type I diabetes mellitus in the BB rat were examined. Concanavalin A (Sigma Chemical Co, St Louis) stimulation of acutely diabetic BB rat splenocytes increased the Ia-positive cells, but no other lymphocyte subset. Each spleen cell preparation was divided into two and injected into two separate recipients. Thirty-day-old diabetes-prone BB rats received these splenocytes intravenously (62 +/- 5 x 10(6) cells, n = 30) or buffer alone (controls, n = 14). Seventy-seven percent of the cell-injected rats became diabetic before 60 days of age, 15 +/- 1 days after injection. They were glucose intolerant two to three days before onset, with normal fasting glucose. All controls maintained normal glucose tolerance. The morphology revealed intense insulitis in all the rats that became diabetic, and its absence in all the controls. Eighty-three percent of the spleen cell preparations produced the same outcome in both recipients. The cell-injected rats had an increase in lymphocyte counts eight days after injection compared with the controls. The most affected subsets were the pan T cells (OX19+) and helper T cells (W3/25+). While the rats that ultimately became diabetic had a decrease of their lymphocyte subsets to control levels between eight and 14 days, the injected rats that maintained normal glucose tolerance maintained elevated T cells. We conclude that (1) adoptive transfer of diabetes occurs in the presence of an increase of the helper T (W3/25+) lymphocytes after spleen cell injections; (2) glucose intolerance precedes by two to three days fasting hyperglycemia; and (3) while the lymphocyte counts are increased in all recipients of splenocyte preparations, these counts decrease rapidly only in the rats that develop diabetes, possibly by entrapment of lymphocytes in the insulitis.

The effect of diet on the spontaneous insulin dependent diabetic syndrome in the rat

We have fed rats prone to developing spontaneous insulin dependent diabetes mellitus (IDDM) defined diets in which casein was the sole source of protein and the fat content was either menhaden oil, safflower oil, or corn oil. The incidence of IDDM was compared to that in litter mates fed rat chow. Animals receiving the defined diets had a lower frequency of overt IDDM than did animals receiving rat chow. The effect was seen only when the diet was introduced before the animals had reached the age of 30 days. The defined diets did not affect the distribution of peripheral blood T lymphocytes. Rats fed defined diets had decreased intensity of expression of Class I major histocompatibility complex (MHC) products on the endocrine cells of the pancreas compared to animals receiving rat chow.

IDDM in BB rats. Enhanced MHC class I heavy-chain gene expression in pancreatic islets

Modulation in major histocompatibility complex (MHC) gene expression correlates with the inflammatory reactions that occur during graft rejection and autoimmune disease. We analyzed the expression of class I and II MHC genes in the pancreatic islets of prediabetic and newly diabetic BB rats by immunohistochemistry of tissue sections and Northern blotting of RNA extracted from isolated islets. We show that enhanced levels of MHC class I heavy-chain RNA are present in pancreatic islets before overt inflammation and the onset of insulin-dependent diabetes mellitus (IDDM) in the spontaneously diabetic BB rat. Immunohistochemical analysis revealed enhanced class I antigen expression throughout the pancreatic islets of newly diabetic animals but no induction of class II antigen on endocrine cells within the islet. Varying degrees of inflammatory infiltrate were observed in the sections exhibiting enhanced class I antigen expression or in nearby serial sections. Southern blot analysis revealed no restriction-fragment-length polymorphism or amplification of the endogenous class I heavy-chain genes compared with those of seroidentical disease-resistant Wistar-Furth rats. I-A alpha and I-E alpha hybridizing RNA appeared de novo before overt diabetes, although concomitantly with T-lymphocyte-receptor beta-chain and interferon-gamma gene hybridizing RNA and after MHC class I heavy-chain RNA enhancement was observed. These data indicate the possibility that enhanced class I heavy-chain gene expression plays a role in the progression of IDDM.

Association of susceptibility to spontaneous diabetes in rat with genes of major histocompatibility complex

This study was designed to map the diabetes susceptibility gene(s) associated with the rat major histocompatibility complex (MHC) RT1. We have crossed spontaneously diabetic male rats bearing the recombinant RT1r8 haplotype with female rats of the AC1.1r4 congenic strain. Three diabetic rats were determined to be homozygous for the r4 haplotype by serotyping. The absence of recombination within the MHC was confirmed by inspection of restriction-fragment-length patterns of the diabetic animals and the parental strains. In conjunction with previous breeding studies, this study maps the diabetes susceptibility gene to the right of the RT1-A locus and to the left of the RT1-C locus. A low incidence of diabetes in the F2 (4.5%) emphasizes the multifactorial nature of the susceptibility. The presence of depressed responsiveness of peripheral blood lymphocytes to concanavalin A stimulation increases the prevalence of the overt disease. An unusual feature of the diabetic syndrome in this study is the sparse or absent pancreatic lymphocytic inflammatory response, with true insulitis being a rare finding.

Complete sequential regeneration of graft-vs.-host-induced severely dysplastic thymuses. Implications for the pathogenesis of chronic graft-vs.-host disease

This study presents the sequential morphologic regeneration of graft-vs.-host (GVH)-induced dysplastic thymuses in long-term survivors of GVH reactions. GVH reactions were induced in adult C57BL/6xAF1 (B6AF1) hybrids by injecting 20 x 10(6) A strain parental lymphoid cells (PLC). Starting on day 30 after GVH induction, five to ten animals were randomly selected from a pool of GVH-reactive mice and killed at various times. Each animal was tested for thymic histology and T cell functions. Thymuses taken on day 30 after GVH induction displayed severe dysplasia as characterized by lymphocytic depletion, complete effacement of cortico-medullary demarcation, and reduction and total loss of medullary epithelial cells or both. Starting by days 60-70 after GVH induction, at least four stages of thymic regeneration were identified. Day 60-70 thymuses displayed cortical regeneration and the reappearance of cortico-medullary demarcation. The medulla of these thymuses, although containing dark individual epithelial cells and numerous lymphocytes, was devoid of pale epithelial cells (stage 1). The medulla of thymuses on day 100 after GVH induction displayed a few sparcely distributed pale epithelial cells and numerous lymphocytes as well as dark epithelial cells (stage 2). The medulla of thymuses examined 130 days after GVH induction displayed numerous pale individual epithelial cells and a few pale epithelial cell clusters. Such thymuses also showed a reduction in the number of medullary lymphocytes (stage 3). Finally, the medulla of thymuses 150-160 days after GVH induction displayed numerous pale epithelial cell clusters and Hassall's bodies. These thymuses were indistinguishable from normal adult thymuses (stage 4). All of the animals tested up to day 130 after GVH induction showed no significant T cell function. Animals displaying stage 4 of thymic regeneration showed significant proliferative responses to T cell mitogen, concanavalin A (conA), and six of ten animals also displayed a few plaque forming cells (PFC) to sheep red blood cells (SRBC) in their spleens. Furthermore, all animals (10 of 10) killed on day 180 after GVH induction displayed significant T cell functions.(ABSTRACT TRUNCATED AT 400 WORDS)

Class I and II major histocompatibility complex gene product expression by a rat insulinoma cell line in vitro following exposure to gamma interferon

A study of Class I and II major histocompatibility complex gene product expression by a rat insulinoma cell line (RINm5F) was performed using monoclonal antibodies and immunoperoxidase techniques. RINm5F cells were incubated with different concentrations of gamma interferon. RINm5F cells exhibit low levels of Class I molecules and are normally devoid of Class II gene products. Upon exposure to gamma interferon, RINm5F cells showed a dramatic increase in Class I expression. This expression was homogenous and could be detected on all cells after 18 h of incubation with as little as 1 unit/ml of interferon. In contrast, de novo Class II expression was not homogeneous and required 36 h of incubation with 10 units/ml of interferon. The number of RINm5F cells expressing Class II antigens was dose- and time-dependent. Interferon treatment did not affect the morphology of RINm5F cells as determined by ultrastructural analysis. Withdrawal of interferon from the culture medium for as long as 78 h diminished but did not abolish the expression of Class I and Class II molecules already induced. The ability of interferon to enhance expression of Class I gene products and induce de novo expression of Class II molecules on B-cell-derived RINm5F cells supports the hypothesis that aberrant expression of major histocompatibility complex gene products on pancreatic B cells may be an important factor in triggering the immune response in Type 1 (insulin dependent) diabetes mellitus.

Association between the degree of thymic dysplasia and the kinetics of thymic NK cell activity during the graft-versus-host reaction

In this study, by employing different cell doses and parent into F1 hybrid combinations, we have investigated the relationship between the severity of thymic medullary dysplasia and the kinetics of thymic natural killer (NK) cell activity after the induction of graft-versus-host (GVH) reactions. GVH reactions were induced by injecting different doses (30, 20, 10 X 10(6] of C57BL/6 (B6) of A parental lymphoid cells (PLC) into non-X-irradiated adult B6xAF1 (B6AF1) mice. On different days after the induction of GVH reactions, the thymuses were examined histologically and thymocyte NK cell activity was tested by using YAC targets. Our results show that, depending upon the genotype and dose of PLC injected, various degrees of thymic medullary dysplasia (mild, moderate, or severe) can be induced. Furthermore, severe to moderate thymic medullary dysplasia is observed only in those groups of GVH-reactive mice in which thymic NK cell activity occurs early and increases rapidly. In contrast, when mild thymic medullary dysplasia or no thymic alterations was observed, thymic NK cell activity peaked later and was of lower intensity than that of the groups with moderate to severe lesions. These results suggest an association between the degree of thymic medullary dysplasia and the kinetics of NK cell activity in the thymus. Furthermore, the different degrees of thymic medullary dysplasia as described here may serve as a powerful tool to study the role of thymic medullary dysplasia in determining the duration of T-cell immunodeficiency associated with the GVH reactions.

Prevention of murine graft-versus-host disease by inducing and eliminating ASGM1+ cells of donor origin

In this study anti-asialo GM1 antibodies (anti-ASGM1) were used to further characterize the effector cells responsible for graft-versus-host (GVH)-induced histopathological lesions: Two different types of ASGM1+ cells were identified: an endogenous ASGM1+ population and an induced ASGM1+ population. Both of the ASGM1+ cell populations exhibited natural killer (NK) cell activity, as assessed by their ability to lyse YAC tumor targets in vitro. Donor C57BL/6 (B6) mice were treated in vivo with anti-ASGM1 to eliminate endogenous ASGM1+ cells. ASGM1+ cells were induced in B6 donor mice by treating the animals with 15 x 10(6) B6 x AF1 (B6AF1) lymphoid cells for 44-48 hr. The induced ASGM1+ cells were eliminated by in vivo treatment with anti-ASGM1. GVH reactions were induced by injecting B6 lymphoid cells into B6AF1 mice. Prior to GVH induction the B6 donor cells were tested for NK cell activity against YAC tumor target cells in vitro and for T and B cell functions by mitogen responses in vitro. GVH reactions were determined by splenomegaly, suppression of the plaque-forming cell (PFC) response to sheep red blood cells (SRBC), suppression of the T and B cell mitogen responses, and the development of GVH-associated histopathological alterations in the thymus, liver, and pancreas. Donor lymphoid cells depleted of endogenous ASGM1+ cells were effective at inducing splenomegaly, severe suppression of immune functions, and histopathological lesions. Donor lymphoid cells depleted of both the endogenous and induced ASGM1+ cells displayed normal T cell mitogen responses and were capable of inducing splenomegaly and partial suppression of the PFC response to SRBC when injected into B6AF1 recipients, however, these lymphoid cells failed to induce both GVH-associated histopathological lesions and severe suppression of T and B cell mitogen responses. These results suggest that semiallogeneic stimulation induces an ASGM1+ population in the donor inoculum that displays NK cell-like function (YAC killing) and that plays a crucial role in inducing GVH-mediated histopathological lesions and severe immunosuppression of both T and B cell responses.

Intermediate filament proteins and actin isoforms as markers for soft tissue tumor differentiation and origin. II. Rhabdomyosarcomas

A series of 15 rhabdomyosarcomas was examined by light microscopy, transmission electron microscopy, two-dimensional gel electrophoresis (2D-GE) and indirect immunofluorescence, the latter using monoclonal or affinity-purified polyclonal antibodies to desmin, vimentin, alpha-smooth muscle and alpha-sarcomeric (alpha-sr) actins. By light microscopy, the authors diagnosed 1 botrioid, 1 alveolar, and 7 embryonal rhabdomyosarcomas, 4 pleomorphic spindle cell sarcomas, and 2 spindle cell sarcomas, one nondistinct, the other with a hemangiopericytomatous pattern. By transmission electron microscopy, 13 neoplasms disclosed rhabdomyoblastic differentiation; the remaining 2, myogenic differentiation. By immunofluorescence microscopy, all neoplasms expressed vimentin and alpha-sr actin, 12 expressed, in addition, desmin, and 1 expressed alpha-smooth muscle actin. Among the 11 neoplasms studied by means of 2D-GE, 7 demonstrated an alpha-actin spot, while 4 showed only beta and gamma spots. One tumor disclosed, in addition to alpha, beta, and gamma spots, a spot with a molecular weight corresponding to actin, but more acidic than alpha-actins. This study demonstrates that alpha-sr actin antibody represents a valuable marker for the diagnosis of rhabdomyosarcoma, because it was present in all neoplasms, including the one negative for desmin. This antibody further allowed the recognition of pleomorphic variants and morphologically atypical forms of rhabdomyosarcomas. The presence of alpha-smooth muscle actin in 1 case of rhabdomyosarcoma suggests that this actin isoform may be expressed during skeletal muscle differentiation.

Diabetes prevention in BB rats by frequent blood withdrawal started at a young age

The BB rat diabetic syndrome has been prevented by various immunosuppressive and reconstitution measures. We observed an effect of multiple blood samplings on diabetes incidence and examined its immunological correlates. Individual litters were divided into two groups; one was sampled and the other was sham sampled as the control group. Sixty-four diabetes-prone and 59 non-diabetes-prone rats were studied. The sampled rats had blood removed at 15 (28% of total blood volume), 30 (30%), 50 (21%), 75 (16%), and 120 days of age. The sham-sampled control rats had blood removed only at 120 days of age. The incidence of diabetes in the sampled group was markedly lower than that of their sham-sampled littermates (22 vs. 78%). This result was associated with a correction of their OX19+ (pan-T-lymphocytes) and W3/25+ (helper/inducer) T-lymphocyte-number defects. An increase in lymphocyte subsets was also seen in the non-diabetes-prone BB rats, significant for all but the OX19+ cells. Islet pathology and pancreatic insulin content were consistent with metabolic outcomes. The effect of blood withdrawal thus has implications for understanding the pathogenesis of both the diabetes syndrome and the lymphopenia of the BB rat. Furthermore, it suggests that a stimulation of lymphopoiesis by blood withdrawal (analogous to that of erythropoiesis) may be a hitherto unrecognized physiological response in normal animals.

Major histocompatibility complex gene product expression on pancreatic beta cells in acutely diabetic BB rats

Type I diabetes mellitus was induced in young, diabetes-prone BB rats by the passive transfer of concanavalin A-activated T lymphocytes from the spleens of acutely diabetic BB rats. The pancreas of the recipients was examined 1-2 days after the onset of glycosuria by immunocytochemistry by means of monoclonal antibodies for determining whether 1) Class I and/or II major histocompatibility gene complex (MHC) products were expressed on beta cells and 2) the mononuclear cell infiltrates were represented by T cells. Marked expression of Class I MHC gene products was evident on beta cells. In contrast, Class II MHC gene products were not identified on normal-appearing beta cells. Dendritic cells dispersed throughout the acinar and interstitial pancreas were markedly increased in number. The mononuclear cell infiltrate contained few cells (1-15%) recognized by a pan-T cell marker. Although it is possible that this passive transfer model might differ considerably from the spontaneously occurring diabetic state in the rat, this study suggests that 1) Class I, rather than Class II, MHC gene expression may be pivotal to beta-cell injury in diabetic rats, and 2) non-T cells may constitute an effector cell population central to beta-cell necrosis in Type I diabetes mellitus.

Molecular basis of selected primary immunodeficiency disorders

Three primary immunodeficiency conditions are discussed: X-linked agammaglobulinemia, severe combined immunodeficiency, and the X-linked lymphoproliferative syndrome. Each condition is associated with a fascinating history since publication of the original description. To a large extent, the immunologic features of these conditions have been defined. Now, the power of recombinant DNA technology is being employed to dissect the molecular mechanisms central to each disease. This review traces the history of these X-linked conditions. Particular emphasis is focused on the molecular defects thus far exposed. In the end, the knowledge provided by this technology will facilitate genetic counseling, define the nature of the gene defects, provide a logical rationale for therapy, and elucidate the role of the X chromosome in lymphocyte ontogeny.

Kinetics of natural killer cell cytotoxicity during the graft-versus-host reaction. Relationship between natural killer cell activity, T and B cell activity, and development of histopathological alterations

The relationships between splenic natural killer (NK) cell cytotoxicity, T and B cell function, and the development of histopathological lesions in the liver and pancreas have been studied during the course of graft-versus-host (GVH) reactions. GVH reactions were induced in (C57BL/6 X A)F1 (B6AF1) hybrids by different doses, (10,20 and 30 X 10(6)) of either parental strain C57/BL6 (B6) or A lymphoid cells. Splenic NK cell cytotoxicity was studied by employing YAC-1, an NK-cell-sensitive target. Splenic T and B cell function were assessed by mitogen responsiveness to concanavalin A, phytohemagglutinin, and Escherichia coli lipopolysaccharide, and by the in vitro plaque-forming cell response to sheep red blood cells. Histopathological lesions characteristic of GVH reactions were recognized at a time (day 8 after GVH induction) when both T and B cell functions were totally suppressed and NK cell activity was greatest. The severity of histopathological alterations later (day 16 after GVH induction) correlated with an early peak in NK cell cytotoxicity rather than with the overall NK cell activity. When low doses (10,20 X 10(6)) of B6 cells were employed to induce GVH reactions, a significant increase in NK cell activity was observed, yet neither histopathological alterations nor suppression of T and B cell functions were observed. The killing of YAC-1 targets by splenocytes obtained from the different GVH combinations could not be abrogated by pretreatment with anti-Thy 1.2 serum plus complement, suggesting that T lymphocytes were not central to this cytolytic process. These experiments demonstrated that: (1) an inverse relationship between T and B cell function and NK cell activity was observed early after GVH induction, (2) the severity of histopathological lesions and immunosuppression, as well as the degree of overall augmented NK cell activity, was determined by the dose and genotype of donor cells injected to induce GVH reactions, and (3) GVH-associated moderate-severe lesions occurred only in groups in which NK cell activity peaked early--whereas when NK cell activity peaked later, either mild or no lesions were observed, suggesting that the early rapid increase of NK cell activity may be useful for predicting the severity of GVH pathogenesis.

Graft-versus-host reactions in the beige mouse. An investigation of the role of host and donor natural killer cells in the pathogenesis of graft-versus-host disease

To investigate the role of natural killer (NK) cells in the induction and pathogenesis of graft-versus-host (GVH) disease, +/beige (+/bg; normal NK cell activity) and beige/beige (bg/bg; deficient NK cell activity) parental C57BL/6 (B6) lymphoid cells were used to induce GVH reactions in either B6 X C3H/Hej +/bg (+/bgF1) or B6 X C3H/HeJF1 bg/bg (bg/bg F1) hybrid mice. When B6 bg/bg parental lymphoid cells (PLC) were injected into bg/bg F1 mice, early splenomegaly, early severe suppression of the plaque-forming cell (PFC) response to sheep red blood cell (SRBC), and only partial suppression of T cell mitogen responses to concanavalin A (Con A) and phytohemagglutin (PHA) were observed on day 12 after GVH induction. In the same GVH combination, slightly augmented NK cytotoxic activity was induced and no GVH-induced moderate-to-severe pathological alterations in the liver and pancreas were observed. When bg/bg PLC were injected into +/bg F1 mice, early splenomegaly and pronounced immunosuppression of the PFC response to SRBC and partial suppression of Con A and PHA responses were observed on day 12 after GVH induction. In this combination (bg/bg----+/bg F1), significant NK cell activity was induced, but no moderate-to-severe histopathological alterations were observed. In contrast, when B6 +/bg PLC were injected into either +/bg F1 or bg/bg F1 hybrids, early splenomegaly, and severe immunosuppression of both the PFC response to SRBC and the T cell mitogen responses to Con A and PHA were observed by day 12--which persisted until day 30 after GVH induction. Furthermore, high NK cell activity was recorded and moderate-to-severe histopathological alterations appeared in both +/bg F1 and bg/bg F1 recipients. These results show that the bg/bg PLC can induce GVH-associated early splenomegaly and immunosuppression of the PFC response to SRBC in both the bg/bg F1 and +/bg F1 hybrids, but that it failed to induce moderate-to-severe histopathological alterations, even though NK cell activity of host origin was activated during GVH reactions. Conversely, when +/bg donor cells were used to induce the GVH reaction, splenomegaly and immunosuppression, as well as moderate-to-severe histopathological lesions were induced. These results suggest that donor NK cells rather than host NK cells play an active role in GVH-associated tissue damage, which in turn contributes to the long-term suppression.

Response to cyclosporine administration at onset of diabetes in BB rats

The metabolic and immunological effects of cyclosporine A given at onset of spontaneous Type I diabetes in BB rats were examined, as an analogy to the current use of this agent in newly-diagnosed human diabetics. Diabetes-prone (BBdp) rats were monitored until appearance of hyperglycemia, at which time treatment with both cyclosporine (10 mg/kg/day) and insulin was immediately started. Cyclosporine induced no remission in any rats and did not affect their daily insulin requirements. After 9 weeks of cyclosporine treatment, islet morphology showed the typical "end-stage" picture in all rats, with essentially total beta cell loss. Pancreatic insulin contents were less than 1% of normal levels. During the 9 weeks of cyclosporine treatment, there was a decrease in numbers of peripheral blood Ia-positive lymphocytes, an increase in OX8+ lymphocytes (suppressor/cytotoxic and natural killer cells) but no change in the other subsets. There was a significant increase in plasma creatinine. We conclude that this dose of cyclosporine started at onset of diabetes in BB rats is unable to arrest and/or reverse the beta cell destructive process.

Intermediate filament proteins and actin isoforms as markers for soft tissue tumor differentiation and origin. I. Smooth muscle tumors

A series of 3 benign and 10 malignant smooth muscle (SM) neoplasms and of 2 malignant fibrous histiocytomas was examined by light microscopy, transmission electron microscopy, two-dimensional gel electrophoresis (2D-GE) and indirect immunofluorescence, using polyclonal monospecific or monoclonal antibodies to desmin, vimentin, cytokeratin, alpha-SM and alpha-sarcomeric (alpha-SR) actins. Benign neoplasms displayed typical light-microscopic features of SM, whereas leiomyosarcomas demonstrated variations in their histologic pattern. In 6 sarcomas, light microscopy suggested a SM differentiation, whereas in the other 4, a predominant nondistinctive spindle-cell pattern was observed. By transmission electron microscopy, all 13 neoplasms showed the minimal essential features of SM differentiation. Immunofluorescence disclosed heterogeneity of cytoskeletal protein expression: 5 neoplasms (3 benign and 2 malignant well-differentiated) expressed desmin, vimentin, and alpha-SM-actin; 2 malignant neoplasms expressed desmin and vimentin; 1 malignant neoplasm expressed desmin, vimentin and alpha-SR actin; 1 malignant neoplasm expressed vimentin and alpha-SR actin; and 4 malignant neoplasms expressed vimentin alone. By 2D-GE, 3 benign and 4 malignant SM neoplasms expressed alpha, beta, and gamma actins, and the remaining expressed only beta and gamma actins. The presence of alpha-SM actin in all benign neoplasms and in 2 well-differentiated leiomyosarcomas suggests that this actin isoform reflects a high degree of cellular differentiation. In 2 leiomyosarcomas, alpha-SR actin was detected by immunofluorescence, which suggested a skeletal muscle differentiation of these neoplasms. This study supports the assumption that leiomyosarcomas represent a heterogeneous group of neoplasms and furnishes new criteria for their characterization.

Immunological and metabolic concomitants of cyclosporin prevention of diabetes in BB rats

The metabolic and immunological effects of cyclosporin given to prevent diabetes in BB rats were examined. Diabetes-prone (BBdp) and normal (BBn) BB rats received either oral cyclosporin (10 mg X kg-1 X day-1 or its vehicle from age 30-150 days. Six of 21 (29%) vehicle-treated rats became glycosuric, with hyperglycemia, weight loss, and unremitting insulin requirements, and showed destruction of islet beta-cells. Five of 24 (21%) cyclosporin-treated rats became glycosuric, but none demonstrated weight loss, all required insulin only intermittently after onset, and all showed persistence of islet beta-cells. Cyclosporin induced hypoinsulinemic glucose intolerance in BBn rats. Cyclosporin inhibited the normal rise with age of peripheral blood lymphocyte cell numbers, identified with monoclonal antibodies. OX19+ (pan-T) and W3/25+ helper T-lymphocytes were affected, and there was an increase in the large W3/13+ OX19- population characteristic of BBdp rats; in addition, this subset appeared in BBn rats. Cyclosporin also caused the appearance and/or increase in both BBdp and BBn rats of W3/25+ OX19- and OX8+ OX19- subsets. Suppressor/cytotoxic (OX8+) T-lymphocytes and Ia+ cells were less affected. The incidence of hyperglycemia and glycosuria was therefore unaltered by cyclosporin, although the diabetic syndrome was milder. BBn rats receiving cyclosporin showed glucose intolerance, suggesting that in BBdp rats, the net effects of immunosuppression on beta-cell destruction may have been counterbalanced by the direct effect on the same cells. The attenuation of diabetes in BBdp rats occurred through further immunosuppression rather than by correction of its preexisting immunodeficiency.