The role of CD4+ helper T cells in the destruction of microencapsulated islet xenografts in nod mice

Islet transplants for large numbers of patients with diabetes will require xenografts. Microencapsulation is an appealing method for islet xenografting. However, graft function has been limited by a cellular reaction, particularly intense in spontaneously diabetic, NOD mice. The purpose of this study was to elucidate the mechanism of this reaction. Poly-1-lysine-alginate microcapsules containing 4000-12,000 dog or 1800-2000 rat islets were xenografted intraperitoneally into streptozotocin (SZN)-diabetic C57BL/6J and NOD mice, with or without recipient treatment with GK 1.5 (anti-CD4 monoclonal antibody) (20-30 microliters i.p. every 5 days, begun on day -7. Grafts were considered technically successful if random blood glucose (BG) was normalized (less than 150 mg/dl) within 36 hr. Graft failure was defined as BG greater than 250 mg/dl. Dog and rat islets in microcapsules normalized BG in both SZN and NOD mice within 24 hr routinely. Empty microcapsules and GK 1.5 treatments alone did not affect BG. NODs destroyed both microencapsulated dog and rat islets more rapidly than did SZN-diabetic mice (P less than .01). Graft biopsies showed an intense cellular reaction, composed of lymphocytes, macrophages and giant cells, and no viable islets. GK 1.5 treatment significantly prolonged both dog-to-NOD and rat-to-NOD grafts (P less than 0.01). Biopsies of long-term functioning grafts (on days 65-85) demonstrated viable islets and no cellular reaction around microcapsules; 1/4 rat and 1/8 dog islet xenografts continued to function indefinitely in NOD recipients, even after cessation of GK 1.5 therapy. Prediabetic NODs receiving encapsulated dog or rat islets mounted a moderate cellular reaction to grafts. Empty microcapsules excited no cellular reaction in diabetic or prediabetic NODs. We conclude that the NOD reaction to microencapsulated xenogeneic islets is helper T cell-dependent, and that the target of this reaction is not the microcapsule itself, but the donor cells within.     

Coexistence of AIDS and lupus nephritis: a case report

We report the first case of membranous lupus nephritis occurring in a child with congenital AIDS. Hypocomplementemia, elevated titers of anti-nuclear antibody and antibody to double-stranded DNA supported the diagnosis of associated systemic lupus erythematosus (SLE). The pathogenetic implications of this coexistence of AIDS and SLE are discussed.     

Lectin characterization of cystogenesis in the SBM transgenic model of polycystic kidney disease.

The generation of a novel transgenic mouse model of polycystic kidney disease with a construct (SBM) that links the coding region of the c-myc proto-oncogene to the simian virus 40 enhancer and beta-globin promoter was previously reported (see reference 1). In order to determine the site of origin and histogenesis of renal cysts in this model, lectin/immunohistochemical and electron microscopic studies on mice of varying ages (from birth to adulthood) are described here. Cysts are detectable at birth and increase in number and diameter with age. Cysts predominantly involve the collecting tubules of young transgenic mice but progressively affect the proximal tubules with advancing age. A minority of cysts are of distal tubular origin in all age groups studied. Tubular hyperplasias are primarily reactive with proximal tubular markers and appear to precede the development of proximal tubular cysts in adult mice. This particular phenotypic evolution of polycystic kidney disease with advancing age suggests that the cystogenic potential of the transgene is modulated by yet unidentified tubular segment-specific responses.     

The synthesis and localization of alternatively spliced fibronectin EIIIB in resting and thrombin-treated megakaryocytes

There are several species of alternatively spliced fibronectin (FN). One of these, FN EIIIB, is primarily present in embryonic and in proliferating and migrating cells and is believed to be important for cell maturation. We have studied the synthesis, localization, and secretion of this FN isoform in isolated guinea pig megakaryocytes, nonmegakaryocytic bone marrow cells, and platelets. There was 7.5 times more general FN in megakaryocytes than in nonmegakaryocytic cells based on the analysis of equivalent amounts of protein. FN EIIIB was detected by Western blotting in megakaryocytes but not in nonmegakaryocytic cells present in bone marrow. Neither megakaryocytes nor platelets secreted FN EIIIB, while megakaryocytes secreted 25.3% +/- 4.6% general FN and platelets secreted about 61% general FN in response to thrombin. Analysis of immunostained cells by confocal microscopy revealed that FN EIIIB had been redistributed to the surface of megakaryocytes in response to thrombin. Synthesis was studied by metabolic labeling, and megakaryocytes were shown to synthesize FN and FN EIIIB. Thus, megakaryocytes and platelets are among a small number of adult cells and tissues that synthesize and contain FN EIIIB. The expression of FN EIIIB on the megakaryocyte surface may influence migration and maturation.     

Anti-idiotypic antibodies specific for HLA in heart and kidney allograft recipients

Chronic rejection is the major threat to both heart and renal allograft survival. We have explored the possibility that some patients with anti-donor HLA antibodies (Ab1) develop specific anti-idiotypic antibodies (Ab2) which suppress the production of Ab1, and subsequently, the progression of chronic rejection. analysis of Ab2 in sera obtained from Ab1 producers showed that 22% of heart and 18% of kidney recipients produced Ab2. The 4- and 5-year actuarial graft survivals in Ab2 producers were 100% and 83%, respectively, compared to 57% in patients who formed Ab1 but not Ab2 (p<0.004). Patients carrying the DR2 alleles, DRB1*1501,*1502 or*1601 were at a lower risk of producing anti-donor HLA antibodies.     

Differential activities of the RET tyrosine kinase receptor isoforms during mammalian embryogenesis

The RET receptor tyrosine kinase has a critical role in kidney organogenesis and the development of the enteric nervous system. Two major isoforms, RET9 and RET51, differ in the amino acid sequence of the C-terminal tail as a result of alternative splicing. To determine the roles of these isoforms in vivo, we used targeted mutagenesis to generate mice that express either RET9 or RET51. Monoisoformic RET9 mice, which lack RET51, are viable and appear normal. In contrast, monoisoformic RET51 animals, which lack RET9, have kidney hypodysplasia and lack enteric ganglia from the colon. To study the differential activities of the two RET isoforms further, we generated transgenic mice expressing ligand-dependent and constitutively active forms of RET9 or RET51 under the control of the Hoxb7 regulatory sequences. Such RET9 transgenes are capable of rescuing the kidney agenesis in RET-deficient mice or causing kidney hypodysplasia in wild-type animals. In contrast, similar RET51 transgenes fail to rescue the kidney agenesis or cause hypodysplasia. Our findings show that RET9 and RET51 have different signaling properties in vivo and define specific temporal and spatial requirements of c-Ret function during renal development and histogenesis of the enteric nervous system.     

Interstitial nephritis related to nonsteroidal anti-inflammatory agents and beta-lactam antibiotics: a comparative study of the interstitial infiltrates using monoclonal antibodies

Acute interstitial nephritis (AIN) is a common pattern of renal injury induced by therapeutic agents. In order to characterize the types of mononuclear leukocytes infiltrating the kidney in drug-induced interstitial nephritis, a panel of monoclonal antibodies (Leu1, Leu3a, OKT8, OKM1, Leu14, OKT17, IL-2) was applied to cryostat sections of 13 renal biopsies (five non-steroidal anti-inflammatory agents (NSAID) (Group I); five beta-lactam antibiotics (Group II), 3 miscellaneous (Group III]. The majority of infiltrating mononuclear leukocytes were Leu1-positive T cells (71.7 +/- 18.7%), followed by monocytes (15.2 +/- 7.7%) and B cells (7.4 +/- 9.1%). Leu3a/OKT8 ratio was 0.954 +/- 0.341. Rare cells reacted with antibody to the interleukin-2 receptor (1.4 +/- 1.2%). No statistically significant differences could be found in the percentages of T lymphocytes, B lymphocytes, monocytes, activated (IL-2+) T cells or Leu3a/OKT8 (helper/suppressor) ratios in the three groups. In Group II, the following pathologic correlations were seen: Leu3a/OKT8 versus interstitial inflammation (R = -0.848), percent Leu3a versus interstitial inflammation (R = -0.818), percent OKT17 versus tubulitis (R = 0.785), percent Leu14 versus tubular atrophy (R = -0.891), and interstitial edema (R = 0.965). Our findings support a role for cellular immune mechanisms in the pathogenesis of AIN related to both NSAIDs and beta-lactam antibiotics.     

Focal segmental membranous glomerulonephropathy associated with other glomerular diseases

In four patients with the nephrotic syndrome, renal biopsy revealed focal segmental membranous glomerulonephropathy (FSMGN) associated with the histologic patterns of "nil" disease (two cases), hereditary nephritis and diffuse diabetic glomerulosclerosis. The occurrence of FSMGN in association with other glomerular diseases, presumably unrelated to immune complex deposition, is infrequent in our experience. Rather than necessarily representing an early stage or milder form of membranous glomerulonephropathy, it may be an epiphenomenon. This interpretation has prognostic and therapeutic implications and raises important pathogenetic questions. In particular, this study suggests that in some instances, preexisting functional and structural abnormalities may play a role either in the deposition of preformed circulating immune complexes or in the local formation of immune complexes.