The graft-versus-host reaction and immune function. II. Recruitment of pre-T-cells in vivo by graft-versus-host-induced dysplastic thymuses following irradiation and bone marrow treatment

The graft-versus-host (GVH) reaction induces thymic dysplasia and an arrest in T cell differentiation. Studies were performed to test the effect of irradiation and reconstitution with bone marrow on GVH-induced thymic dysplasia and T cell differentiation. GVH reactions were induced in CBAxAF1 adult mice by the injection of A strain lymphoid cells. All GVH-reactive mice were immunosuppressed by day 7 after GVH induction and thymic dysplasia was evident by day 24. Forty days after the induction of the GVH reaction the mice were irradiated (850 rads) and repopulated with 10-15 X 10(6) syngeneic or parental bone marrow cells. Thirty days after irradiation and bone marrow reconstitution, GVH-reactive mice were used for histological and functional studies. These mice displayed near-normal thymus morphology with scattered epithelial cells in the medulla, and normal numbers of Thy-1-positive cells. Donor cells had totally repopulated thymuses of irradiated bone marrow reconstituted mice by day 19 after irradiation. T helper cell function did not recover in the reconstituted mice. These results suggest that (1) the process responsible for GVH-induced thymic dysplasia is radiosensitive, and (2) the thymus has the potential to regenerate a normal structure, but fails to regain normal function.

Immune dysfunction in diabetes-prone BB rats. Interleukin 2 production and other mitogen-induced responses are suppressed by activated macrophages

Spleen cells of diabetes-prone BB Wistar rats were found to generate excessively low proliferative responses, and interleukin 2 (IL-2) levels in response to T-dependent mitogens. This abnormality was not due solely to abnormal T cell numbers since: (a) addition of BB spleen cells of BB splenic macrophages to normal major histocompatibility complex (MHC)-matched Wistar Furth (WF) spleen cells resulted in severe suppression of concanavalin A (Con A)-, phytohemagglutinin (PHA)-, and pokeweed mitogen (PWM)-mediated proliferation, and IL-2 production; (b) macrophage depletion from BB spleen cells, but not B cell or T cell depletion, removed completely the suppressive effects of BB cells on WF cells; (c) macrophage depletion greatly enhanced the response of BB lymphocytes to T-dependent mitogens. Although suppressor macrophages could also be found in the spleen of WF control rats they were present in much smaller numbers than in the spleen of BB rats. The suppressive effect of BB macrophages was partially reduced by addition of the prostaglandin synthetase inhibitor indomethacin to cultures. Furthermore, indomethacin (but not catalase or PMA) considerably augmented IL-2 secretion of Con A-stimulated BB spleen cells, but had little effect on WF spleen cells. In contrast, prostaglandins E1 and E2 (PGE1 and PGE2) suppressed IL-2 production. While IL-2 secretion was severely depressed in BB rats unstimulated and lipopolysaccharide (LPS)-stimulated IL-1 secretion by splenic macrophages was normal. BB macrophages did not inactivate IL-2. Low IL-2 production and macrophage-mediated suppression were features of all BB rats tested.

The intermediate filament cytoskeleton of myofibroblasts: an immunofluorescence and ultrastructural study

The intermediate filament cytoskeleton of stromal myofibroblasts from a series of twenty-eight infiltrating ductal breast carcinomas was examined by transmission electron microscopy (TEM) and indirect immunofluorescence (IF), the latter using antibodies to desmin, vimentin and prekeratin. Three cases of fibromatoses, selected as an additional source of myofibroblasts, were processed in the same manner. Stromal myofibroblasts from invasive ductal breast carcinomas rich in actin and readily identified by IF, were most numerous in the "young" edematous mesenchyme, areas corresponding to early stromal invasion or the peripheral invasive cellular front. Within the central sclerotic zone wherein clusters of neoplastic epithelial cells were surrounded by abundant collagen, most stromal cells corresponded by TEM to fibroblasts. In like fashion, myofibroblasts were most numerous in cellular, poorly collagenized portions of fibromatoses. By IF the only detectable intermediate filament protein of myofibroblasts in these two settings was vimentin. Since the appearance of stromal myofibroblasts appears to be associated with stromal invasion by malignant epithelium, their development by modulation of pre-existent periductal fibroblasts is postulated. With the exception of vascular smooth muscle cells and endothelial cells, the only periductal mesenchymal cells shown to contain vimentin were fibroblasts. The lack of desmin in myofibroblasts constitutes evidence against an origin from vascular smooth muscle cells. Because the molecular markers (intermediate filament proteins) of stromal cell differentiation presented quantitative but not qualitative modifications, the transformation of fibroblasts into myofibroblasts is quite likely, suggesting that myofibroblasts may be more closely related to fibroblasts than to smooth muscle cells.

Spontaneous diabetes mellitus syndrome in the rat. IV. Immunogenetic interactions of MHC and non-MHC components of the syndrome

We have examined the frequency of three phenotypic characteristics of the syndrome of spontaneous diabetes (overt IDDM, lymphocytic infiltration of the pancreas, and depression of T lymphocytes) in the offspring of crosses between IDDM BB rats and rats of strains with the same and different RT1 genotypes. On the basis of these observations we propose that there are at least three components of the diabetic syndrome in the rat: (1) a requirement for the RT1u haplotype from the BB strain or a gene in close linkage with the gene coding for this haplotype, (2) a susceptibility for development of insular, periductular, or intraacinar lymphocytic infiltration in the pancreas, and (3) a susceptibility to depression of T lymphocytes. Interactions between these components as well as with other genetic and environmental factors contribute to the full expression of the syndrome.

Spontaneous diabetes mellitus syndrome in the rat. III. Pancreatic alterations in aglycosuric and untreated diabetic BB Wistar-derived rats

The pancreatic alterations in aglycosuric and untreated diabetic BB Wistar-derived rats are described. A common finding, often seen in young aglycosuric rats, is that of discrete foci of periductular and/or acinar aggregates of lymphocytes and macrophages. Sites of periductular mononuclear cell infiltrates usually lack endocrine cells. In contrast, foci of acinar infiltrates, although distinct from the predominant endocrine cell mass in the islets of Langerhans, often contain small numbers of alpha and/or beta cells. It is suggested that these clusters of endocrine cells may in some way be antigenically different from those resident in the principal islets and thus serve as an additional target for the immune system in rats bearing the BB genome. The development of overt diabetes requires a massive destruction of beta cells within the islets of Langerhans. Two forms of diabetes mellitus emerge in untreated animals. The more common, designated unstable diabetes, is severe and lethal unless treated with insulin. Less commonly, a stable type of diabetes mellitus ensues for which insulin therapy is not mandatory. In each, the concentration of pancreatic immunoreactive insulin is profoundly decreased, although relatively greater amounts are present in the stable form. Unstable diabetic rats demonstrate a reduction in the concentration of pancreatic immunoreactive glucagon and somatostatin, suggesting that alpha and delta cells also sustain injury in this model of insulin-dependent diabetes mellitus.

Lymphoproliferative lesions in BB Wistar rats

Fifteen percent of long-term diabetic BB Wistar rats developed abdominal B cell lymphoproliferative lesions which ranged from minute mesenteric aggregates of plasma cells and lymphocytes to malignant lymphoma with features of immunoblastic sarcoma or plasma-cell lymphoma. Lymph nodes in younger BB Wistar rats, both diabetic and nondiabetic, demonstrated variable degrees, often extensive, of paracortical and medullary replacement by plasmacytoid lymphocytes and/or plasma cells. This study documents morphologic abnormalities in lymph nodes of BB Wistar rats, thus providing additional evidence of altered immunity in this model.

B cell lymphoproliferation in spontaneously diabetic BB Wistar rats

Ninety-six spontaneously diabetic BB Wistar rats were maintained for their natural life span and, at death, were autopsied together with 86 age-and sex-matched non-diabetic BB control rats. A 15% incidence of abdominal B cell lymphoproliferative lesions was documented in the diabetic rats compared with 1% incidence in the non-diabetic rats (p less than 0.005). The B cell lymphoproliferative process included minute mesenteric and omental aggregates of plasma cells and small lymphocytes (one rat), atypical partially fibrotic lymphoproliferative mesenteric nodules (three rats), and malignant lymphoma with features of immunoblastic sarcoma (eight rats) or plasma cell lymphoma (two rats). Cytoplasmic immunoglobulin was demonstrated in two of the four lymphomas examined by the peroxidase-antiperoxidase technique, thus confirming their B cell derivation. The striking incidence of B cell lymphoproliferation in this diabetic population is additional evidence of altered immunity in this animal model of insulin-dependent diabetes mellitus.

Dynamic time course studies of the spontaneously diabetic BB Wistar rat. III. Light-microscopic and ultrastructural observations of pancreatic islets of Langerhans

The pancreatic islet alterations were studied in spontaneously diabetic BB Wistar rats and in young (50 and 65 days old) normoglycemic BB rats with the use of light microscopy, immunohistochemistry, and electron microscopy. Three groups of diabetic rats were delineated: 1) early diabetes (1-3 days after detection of glycosuria), 2) stable diabetes (41-63 days after detection), and 3) unstable diabetes (7-22 days after detection). In early diabetes islets were extensively infiltrated by "activated" lymphocytes and macrophages, and B cells demonstrated marked degranulation, injury, and necrosis. Although no consistent changes were recorded in A cells, D cells appeared to be decreased in number. In stable and unstable diabetes, islets were small and markedly depleted of B cells, although more insulin-containing cells were identified in the stable group. The number of A and D cells appeared normal in the stable group, although some A cells appeared altered ultrastructurally. In the unstable group both A and D cells appeared decreased, and ultrastructurally altered A cells were again noted. These findings suggest that although B cells appear to be the principal islet target in this model, A and D cells also sustain cellular injury. Variable degrees of insulitis, B cell degranulation, and necrosis were documented in 65-day-old normoglycemic BB rats, suggesting that the destructive process in the islets is initiated well in advance of the onset of the clinical syndrome. The pancreases from many diabetic and normoglycemic BB rats also demonstrated mononuclear cell infiltrates distinct from insulitis in periductular and/or acinar locations. These infiltrates, not present in controls, appear to represent an additional morphologic expression of the process responsible for initiating the diabetic state.

Epstein-Barr virus in a malignant lymphoproliferative disorder of B-cells occurring after thymic epithelial transplantation for combined immunodeficiency

A fatal disseminated polyclonal malignant lymphoproliferative disorder of B-cells (immunoblastic sarcoma) developed shortly after a second thymic epithelial peritoneal implant in a 5-yr-old girl with combined immunodeficiency. The immunodeficiency was characterized by low T-cell numbers and function, very low levels of thymic hormone, dysgammaglobulinemia, and an inability to mount a primary antibody or cell-mediated response to new antigens. At necropsy, the thymus fulfilled morphological criteria for thymic dysplasia. Epstein-Barr virus (EBV) antigen and DNA were identified in neoplastic infiltrates in the lymph nodes and thymus by immunofluorescence for the EBV nuclear antigen and by EBV-specific complementary RNA/DNA hybridization. No antibodies to nuclear antigen, early antigen, or viral capsid antigen of EBV were identified in the serum. The concurrence of these events suggests that the thymic epithelial implant itself may have been instrumental in the pathogenesis of this neoplasm. It is proposed that the thymus may have provided factors which indirectly potentiated the proliferation of EBV-infected B-cells, possibly by induction of nonspecific T-helper cells and perhaps through other thymic humoral factors. It is suggested that some forms of immunoblastic sarcoma, even when polyclonal, and especially those which arise in immunocompromised hosts, may, in some instances, represent an opportunistic form of EBV-induced B-cell neoplasia.

Stromal myofibroblasts in primary invasive and metastatic carcinomas. A combined immunological, light and electron microscopic study

A series of 23 primary invasive and 7 metastatic carcinomas was examined by light microscopy (LM), transmission electron microscopy (TEM) and immunofluorescence (IF), the latter employing an anti-actin antibody. The results were correlated with macroscopic features such as retraction and consistency. Stromal cells rich in actin, readily identified by IF in firm and retracted carcinomas, were rare or absent in neoplasms lacking these features. TEM established the myofibroblastic nature of these stromal cells. Alternate sections (LM, IF) of each neoplasm demonstrated that myofibroblasts were more numerous in "young" mesenchymal stroma than in densely sclerotic areas. The connective tissue adjacent to intraductal mammary carcinoma lacked myofibroblasts, suggesting that epithelial stromal invasion is required to evoke a myofibroblastic stromal response. Myofibroblasts which possess synthetic (type III collagen) and contractile properties may well contribute to the firm consistency and retraction which characterize many carcinomas. The induction of myofibroblasts might represent an important host stromal response directed toward containment of invasive and/or metastatic carcinoma. This response may be especially important in neoplasms with weak antigenicity and/or slow doubling times.

Myofibroblasts in soft tissue sarcomas

A series of 129 soft tissue sarcomas was examined ultrastructurally to determine in which neoplasms and to what extent myofibroblasts could be demonstrated. Twenty cases of fibromatosis and fasciitis served as controls. Myofibroblasts were identified in all 30 cases of malignant fibrous histiocytoma and all 4 cases of well-differentiated sclerosing liposarcoma. Though most numerous in areas of desmoplasia, in no instance did myofibroblasts constitute the dominant cellular constituent of either neoplasm. Myofibroblasts were identified with lesser frequency and in smaller numbers in fibrosarcoma, synovial sarcoma, malignant hemangiopericytoma and neuroblastoma. None were observed in a wide assortment of diverse sarcomas in which desmoplasia was not a feature. In comparison each lesion judged by light microscopy to represent either fibromatosis or fasciitis was composed principally of myofibroblasts. The demonstration of abundant myofibroblasts within a soft tissue lesion which has been subjected to wide sampling strongly suggests a benign proliferative process as opposed to a malignant neoplasm. It is hypothesized that myofibroblasts observed within collagenized regions of soft tissue sarcomas may constitute an expression of host response to neoplasia.

Animal model of human disease. Diabetes mellitus

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