RESUMO
OBJECTIVES: Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive lysosomal lipid storage disorder that is invariably fatal. NP-C diagnosis can be delayed for years due to heterogeneous presentation; adult-onset NP-C can be particularly difficult to diagnose. We developed a Suspicion Index tool, ranking specific symptoms within and across domains, including family members who have NP-C, to provide a risk prediction score to identify patients who should undergo testing for NP-C. METHODS: A retrospective chart review was performed in 5 centers in Europe and 2 in Australia (n = 216). Three patient types were selected: classic or variant filipin staining NP-C cases (n = 71), NP-C noncases (confirmed negative by filipin staining; n = 64), or controls with at least 1 characteristic symptom of NP-C (n = 81). NP-C signs and symptoms were categorized into visceral, neurologic, or psychiatric domains. Logistic regression was performed on individual signs and symptoms within and across domains, and regression coefficients were used to develop prediction scores for NP-C. Internal validation was performed with the bootstrap resampling method. RESULTS: The Suspicion Index tool has good discriminatory performance with cutpoints for grading suspicion of NP-C. Neonatal jaundice/cholestasis, splenomegaly, vertical supranuclear gaze palsy, cataplexy, and cognitive decline/dementia were strong predictors of NP-C, as well as symptoms occurring in multiple domains in individual patients, and also parents/siblings or cousins with NP-C. CONCLUSIONS: The Suspicion Index tool is a screening tool that can help identify patients who may warrant further investigation for NP-C. A score ≥70 indicates that patients should be referred for testing for NP-C.
Assuntos
Exame Neurológico/métodos , Doença de Niemann-Pick Tipo C/diagnóstico , Doença de Niemann-Pick Tipo C/fisiopatologia , Adolescente , Adulto , Fatores Etários , Criança , Pré-Escolar , Europa (Continente)/epidemiologia , Saúde da Família , Feminino , Humanos , Lactente , Cooperação Internacional , Modelos Logísticos , Masculino , Transtornos Mentais/etiologia , Pessoa de Meia-Idade , Exame Neurológico/normas , Doença de Niemann-Pick Tipo C/epidemiologia , Valor Preditivo dos Testes , Curva ROC , Estudos Retrospectivos , Fatores de Risco , Inquéritos e Questionários , Adulto JovemRESUMO
Pseudoactinomycotic radiate granules, also known as the Splendore-Hoeppli phenomenon represent a response to organic and in-organic foreign substances and can be found at various locations in the body. They are frequently observed in uterine curettages, where they can be misinterpreted as actinomycotic sulfur granules. Here we report a case with Splendore-Hoeppli phenomenon in an intrauterine device (IUD)-associated genital actinomycosis. The morphological features of this phenomenon are presented using special staining methods and electron microscopy and the literature is reviewed.
Assuntos
Actinomicose/patologia , Curetagem , Dispositivos Intrauterinos/efeitos adversos , Actinomyces/isolamento & purificação , Grânulos Citoplasmáticos/patologia , Grânulos Citoplasmáticos/ultraestrutura , Diagnóstico Diferencial , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
BACKGROUND: There is growing evidence of apoptosis in neurodegenerative disease. However, it is still unclear whether the pathological manifestations observed in slow neurodegenerative diseases are due to neuronal loss or whether they are related to independent degenerative events in the axodendritic network. It also remains elusive whether a single, caspase-based executing system involving caspases is responsible for neuronal loss by apoptosis. MATERIALS AND METHODS: Long-term exposure to the microtubule-disassembling agent, colchicine, was used to disrupt the axodendritic network and eventually trigger caspase-3-mediated apoptosis in cultures of cerebellar granule cells. For this model, we investigated the role of Bcl-2 and caspases in neurite degeneration and death of neuronal somata. RESULTS: Early degeneration of the axodendritic network occurred by a Bcl-2 and caspase-independent mechanism. Conversely, apoptosis of the cell body was delayed by Bcl-2 and initially blocked by caspase inhibition. However, when caspase activity was entirely blocked by zVAD-fmk, colchicine-exposed neurons still underwent delayed cell death characterized by cytochrome c release, chromatin condensation to irregularly shaped clumps, DNA-fragmentation, and exposure of phosphatidylserine. Inhibitors of the proteasome reduced these caspase-independent apoptotic-like features of the neuronal soma. CONCLUSION: Our data suggest that Bcl-2-dependent and caspase-mediated death programs account only partially for neurodegenerative changes in injured neurons. Blockage of the caspase execution machinery may only temporarily rescue damaged neurons and classical apoptotic features can still appear in caspase-inhibited neurons.
Assuntos
Apoptose/fisiologia , Caspases/metabolismo , Neurônios/patologia , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Transporte Biológico , Inibidores de Caspase , Morte Celular/efeitos dos fármacos , Células Cultivadas , Cromatina/efeitos dos fármacos , Cromatina/ultraestrutura , Colchicina/farmacologia , Cisteína Endopeptidases , Inibidores de Cisteína Proteinase/farmacologia , Grupo dos Citocromos c/efeitos dos fármacos , Grupo dos Citocromos c/metabolismo , Membranas Intracelulares/efeitos dos fármacos , Leupeptinas/farmacologia , Camundongos , Camundongos Mutantes , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Complexos Multienzimáticos/antagonistas & inibidores , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Fosfatidilserinas/metabolismo , Complexo de Endopeptidases do Proteassoma , Proteínas Proto-Oncogênicas c-bcl-2/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismoRESUMO
Primary cultures of porcine endothelial cells (EC) can only be maintained for a limited number of passages. To facilitate studies of xenogeneic human anti-pig immune responses in vitro, pig microvascular bone-marrow (BM) and macrovascular aortic EC were obtained from our herd of partially inbred miniature swine, homozygous for the major histocompatibility locus, and immortalized with a modified SV40 large T vector. The resulting BM-derived (2A2) and aortic (PEDSV.15) immortalized EC lines showed unlimited growth and EC phenotype as indicated by expression of von Willebrand Factor (vWF) and low density lipoprotein (LDL) receptors as well as by formation of typical cobblestone monolayers. Ultrastructural studies revealed morphological similarities in primary and immortalized EC. Flow cytometry analysis demonstrated constitutive SLA class I expression by all lines whereas SLA class II was only expressed after stimulation with porcine IFNgamma. Furthermore, pig CD34 mRNA was detected by Northern blot analysis in primary and immortalized aortic EC but not in 2A2. Both EC lines expressed a number of myeloid markers, adhesion molecules and xenoantigens, the latter being determined by binding of human natural antibodies. Gene transfer into the porcine EC lines was successfully performed by electroporation or calcium-phosphate transfection, as well as by adenoviral infection. Finally, the functional similarity between primary and immortalized EC was demonstrated in adhesion and cytotoxicity assays. Together, these results suggest that 2A2 and PEDSV. 15 represent valuable tools to study both human cellular and humoral immune responses in vitro against pig EC derived from microvascular and large vessels.
Assuntos
Células da Medula Óssea , Transformação Celular Viral , Endotélio Vascular , Transplante Heterólogo , Animais , Antígenos Transformantes de Poliomavirus , Linhagem Celular Transformada , Eletroporação , Humanos , SuínosRESUMO
The rapidly growing chorionic villi of the human placenta characteristically show constant blood vessel growth and differentiation. In contrast, the underlying decidua reveals tissue remodeling without apparent angiogenesis. Using the chick chorioallantoic membrane (CAM) assay, we found marked inhibition of angiogenesis by the feto-maternal interface tissue derived from nine human placentas obtained minutes after delivery. Inhibition was prevented by the addition of monensin, which blocks the release of synthesized cell products, and was markedly reduced by drying or freezing the tissue before the assay. Histology, combined with statistical analysis of the constituent cell types, correlated inhibition of angiogenesis with the number of fetally-derived extravillous trophoblasts in the feto-maternal interface tissue. Electron microscopy revealed endothelial cell damage in preexisting small (but not large) CAM vessels. We conclude that decidual tissue inhibited angiogenesis by releasing a water soluble factor which was under apparent constant production by vaible trophoblast on the CAM. The extravillous trophoblast population resembles tumor cells in its migratory and invasive properties but, in contrast to tumor induced angiogenesis, it is angiostatic, perhaps to counteract angiogenic proteins leaking from the intervillous space which could be detrimental to the maternal organism if active.
Assuntos
Neovascularização Fisiológica , Placenta/irrigação sanguínea , Alantoide/irrigação sanguínea , Alantoide/efeitos dos fármacos , Alantoide/ultraestrutura , Animais , Embrião de Galinha , Córion/irrigação sanguínea , Córion/efeitos dos fármacos , Córion/ultraestrutura , Vilosidades Coriônicas/irrigação sanguínea , Vilosidades Coriônicas/efeitos dos fármacos , Vilosidades Coriônicas/fisiologia , Vilosidades Coriônicas/ultraestrutura , Decídua/irrigação sanguínea , Decídua/efeitos dos fármacos , Decídua/fisiologia , Decídua/ultraestrutura , Feminino , Humanos , Técnicas In Vitro , Troca Materno-Fetal/fisiologia , Microscopia Eletrônica , Monensin/farmacologia , Neovascularização Fisiológica/efeitos dos fármacos , Placenta/efeitos dos fármacos , Placenta/fisiologia , GravidezRESUMO
The activation of the death receptors, tumor necrosis factor-receptor-1 (TNF-R1) or CD95, is a hallmark of inflammatory or viral liver disease. In different murine in vivo models, we found that livers depleted of gamma-glutamyl-cysteinyl-glycine (GSH) by endogenous enzymatic conjugation after phorone treatment were resistant against death receptor-elicited injury as assessed by transaminase release and histopathology. In apoptotic models initiated by engagement of CD95, or by injection of TNF or lipopolysaccharide into galactosamine-sensitized mice, hepatic caspase-3-like proteases were not activated in the GSH-depleted state. Under GSH depletion, also caspase-independent, TNF-R1-mediated injury (high-dose actinomycin D or alpha-amanitin), as well as necrotic hepatotoxicity (high-dose lipopolysaccharide) were entirely blocked. In the T-cell-dependent model of concanavalin A-induced hepatotoxicity, GSH depletion resulted in a suppression of interferon-gamma release, delay of systemic TNF release, hepatic nuclear factor-kappaB activation, and an abrogation of sinusoidal endothelial cell detachment as assessed by electron microscopy. When GSH depletion was initiated 3 hours after concanavalin A injection, ie, after the peak of early pro-inflammatory cytokines, livers were still protected. We conclude that sufficient hepatic GSH levels are a prerequisite for the execution of death receptor-mediated hepatocyte demise.
Assuntos
Apoptose/fisiologia , Glutationa/deficiência , Fígado/patologia , Fígado/fisiologia , Receptores do Fator de Necrose Tumoral/fisiologia , Amanitinas/farmacologia , Animais , Antígenos CD/metabolismo , Caspases/fisiologia , Morte Celular/fisiologia , Concanavalina A/farmacologia , Citocinas/metabolismo , Dactinomicina/farmacologia , Relação Dose-Resposta a Droga , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Necrose , Inibidores da Síntese de Ácido Nucleico/farmacologia , Receptores do Fator de Necrose Tumoral/metabolismo , Receptores Tipo I de Fatores de Necrose Tumoral , Choque Séptico/mortalidade , Choque Séptico/patologiaRESUMO
We report on a rare distinctive variant of infiltrating ductal carcinoma characterized by sebaceous differentiation of tumor cells. The neoplasm was identified in a lumpectomy specimen from a 45-year-old woman with extensive metastatic disease. In addition to conventional in situ and invasive ductal components, approximately half of the tumor cells exhibited a phenotype resembling tumors of the sebaceous skin appendage with coarsely vacuolated cytoplasm and peripherally displaced nuclei. The sebaceous moiety was also present in the distant metastatic deposits. There was no evidence of mucin production by tumor cells. Ultrastructurally, empty-appearing non-membrane bound vacuoles attested to the sebaceous cells' lipid content. The immunoprofile of the lesion included positivity for cytokeratin and epithelial membrane antigen. Vimentin, S100 protein and carcinoembryonic antigen were not expressed. Most tumor cell nuclei reacted with antibodies to oestrogen and progesterone receptors but failed to show overexpression of the HER2/neu protein. The MIB-1 labeling index averaged 16%. At variance with sebaceous breast carcinomas on record, the present case is notable for its prolonged clinical course.
Assuntos
Adenocarcinoma Sebáceo/patologia , Neoplasias da Mama/patologia , Carcinoma in Situ/patologia , Carcinoma Ductal de Mama/patologia , Adenocarcinoma Sebáceo/química , Adenocarcinoma Sebáceo/cirurgia , Antígenos Nucleares , Biomarcadores Tumorais/análise , Neoplasias da Mama/química , Neoplasias da Mama/cirurgia , Carcinoma in Situ/química , Carcinoma in Situ/cirurgia , Carcinoma Ductal de Mama/química , Carcinoma Ductal de Mama/cirurgia , Citoplasma/ultraestrutura , Feminino , Humanos , Imuno-Histoquímica , Antígeno Ki-67 , Pessoa de Meia-Idade , Invasividade Neoplásica , Proteínas Nucleares/análise , Receptores de Estrogênio/análiseRESUMO
Optimized in vitro formation of strong tissue is a prerequisite for tissue engineering of cardiovascular structures, such as heart valves and blood vessels. This study evaluates different growth media additives as to cell proliferation, extracellular matrix formation, and mechanical characteristics. Biodegradable polymers were seeded with human vascular myofibroblasts. Group A was cultured with standard medium, groups B, C, and D were in addition supplemented with ascorbate, fibroblast growth factor (bFGF), and both respectively. Analysis included histology, electron microsocopy, mechanical testing, and biochemical assays for cell proliferation (DNA) and extracellular matrix (collagen). DNA content increased in all groups, showing significantly more cells in group C and D after 14d. Collagen increased in all groups, except for C. Morphology showed viable, layered cellular tissue, with collagen fibrils after 2w, most pronounced in B and D. Mechanical properties decreased initially, stabilizing after 2w. In conclusion, standard nutrient media were efficient for seeded human vascular cells cultured on biodegradable meshes. Supplementation with bFGF+ascorbate resulted in enhanced early cell proliferation and structurally more mature tissue formation.
Assuntos
Matriz Extracelular/metabolismo , Próteses Valvulares Cardíacas , Coração Artificial , Hidroxiprolina/metabolismo , Fenômenos Biomecânicos , Divisão Celular , Células Cultivadas , Ergonomia , Humanos , Miofibrilas/metabolismoRESUMO
Using a murine model, we studied the effect of agonistic anti-CD95 antibodies (aCD95) on sinusoidal lining cells and a potential protection by caspase inhibition. C3H/HeN mice were intravenously administered aCD95 (10 microgram/mouse) or unspecific IgG (control) in the presence or absence of the caspase inhibitor z-VAD-fmk. Analysis of hepatic microcirculation using intravital fluorescence microscopy revealed severe (P<0.01) sinusoidal perfusion failure and reduced (P<0.05) phagocytic activity of Kupffer cells (KC) within 2 h. Transmission electron micrographs demonstrated loss of integrity of sinusoidal endothelial cells as early as 1 h after aCD95 application, whereas histological manifestation of hepatocellular apoptosis and hemorrhagic necrosis was most pronounced at 6 h. Blocking of caspase activity attenuated (P<0.01) both hepatic microvascular perfusion failure and KC dysfunction. Accordingly, full protection of the liver from apoptotic damage and intact microarchitecture was observed in histological sections after z-VAD-fmk treatment. Mortality rate was 40% 6 h after aCD95 administration, whereas all animals survived in the z-VAD-fmk group (P<0.05). The activation of caspases through CD95 may primarily lead to damage of sinusoidal endothelial cells and hepatic microvascular perfusion failure. Moreover, reduced phagocytic capacity of KC may contribute to accumulation of toxic metabolites released by dying cells at the local site of inflammation, further aggravating liver injury.
Assuntos
Inibidores de Caspase , Inibidores de Cisteína Proteinase/farmacologia , Células de Kupffer/efeitos dos fármacos , Circulação Hepática/efeitos dos fármacos , Receptor fas/efeitos dos fármacos , Alanina Transaminase/sangue , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Aspartato Aminotransferases/sangue , Caspase 3 , Células de Kupffer/enzimologia , Células de Kupffer/fisiologia , Leucócitos/citologia , Fígado/irrigação sanguínea , Fígado/citologia , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C3H , Microscopia Eletrônica , Fagocitose/efeitos dos fármacos , Receptor fas/imunologiaRESUMO
Central nervous system (CNS) involvement is a prominent feature of human immunodeficiency virus (HIV-1) infection. Monocytes and CD4+ T cells traverse the blood brain barrier (BBB), and serve as vehicles for the virus and perpetrators for brain pathology by their production of neurotoxins. In the present study cerebrospinal fluid (CSF) samples from HIV-1-infected patients were analyzed for the presence of chemotactic factors. All 36 CSF samples from the patients were positive for the CXC chemokine interferon-gamma inducible protein (IP-10), which was not detected in CSF samples of 14 controls. The IP-10 concentrations were higher in HIV-1-infected patients with HIV-1 associated neurologic disorders than in those without neurological deficits. In contrast to IP-10, other chemotactic factors including the CC chemokines MCP-1, MIP-1alpha, MIP-1beta and RANTES and the cytokines IL-15 and IL-16 were either not detected or increased in only less than 30% of the patients. Unlike the CSF samples of controls, all CSF samples from HIV-1-infected patients induced chemotaxis of T cells activated with IL-2. The significance of IP-10 as a T cell chemotactic cytokine in HIV-1-infected CSF is shown by (1) the correlation of the IP-10 levels with the extent of T cell chemotaxis, (2) the neutralization of T cell chemotaxis by anti-IP-10 antibodies and (3) the correlation of the chemotactic response of CSF samples on activated T cells and the CSF white cell count in the patients. Our data provide evidence that IP-10 contributes to the accumulation of activated T cells in the CSF compartment in HIV-1-infected individuals.
Assuntos
Complexo AIDS Demência/imunologia , Quimiocinas CXC/síntese química , Fatores Quimiotáticos/líquido cefalorraquidiano , Citocinas , HIV-1/imunologia , Interferon gama/imunologia , Complexo AIDS Demência/líquido cefalorraquidiano , Adulto , Encéfalo/citologia , Encéfalo/imunologia , Líquido Cefalorraquidiano/citologia , Líquido Cefalorraquidiano/imunologia , Líquido Cefalorraquidiano/virologia , Quimiocina CCL3 , Quimiocina CCL4 , Quimiocina CCL5/líquido cefalorraquidiano , Quimiocina CCL7 , Quimiocina CXCL10 , Quimiotaxia/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Contagem de Leucócitos , Proteínas Inflamatórias de Macrófagos/líquido cefalorraquidiano , Masculino , Pessoa de Meia-Idade , Proteínas Quimioatraentes de Monócitos/líquido cefalorraquidiano , Linfócitos T/citologia , Linfócitos T/imunologia , Linfócitos T/virologiaRESUMO
The massive infiltration of synovium with CD4+ T cells during the course of rheumatoid arthritis (RA) implies the expression of chemoattractant factors by resident synovial cells. Therefore, we analyzed the expression of IL-16, a potent chemoattractant for CD4+ T cells, to account for the accumulation of CD4+ T cells in RA. Indeed, IL-16 was found to be significantly elevated in synovial fluid (SF) from patients with RA as compared to non-RA arthritis (p < 0.001), osteoarthritis (p < 0.001) and controls (p < 0.001). Chemotaxis studies showed IL-16 to contribute to the strong chemotactic activities of RA-SF. In situ hybridization (ISH) revealed IL-16 mRNA-expressing cells located within the lining layer of rheumatoid synovial tissue. In the sublining area, only scattered IL-16 transcript-positive cells could be detected, mainly adjacent to blood vessels. By a double-labeling technique, combining ISH for IL-16 mRNA and immunohistochemistry for CD68, synovial fibroblast-like, CD68-negative cells were identified as a major source of IL-16 mRNA within RA synovium. This study demonstrates that synovial fibroblasts produce IL-16 in RA and thus mediate chemoattraction of CD4+ cells into synovial tissue.
Assuntos
Artrite Reumatoide/imunologia , Linfócitos T CD4-Positivos/imunologia , Fatores Quimiotáticos/imunologia , Fatores Quimiotáticos/farmacologia , Quimiotaxia/efeitos dos fármacos , Quimiotaxia/imunologia , Interleucina-16/imunologia , Interleucina-16/farmacologia , Membrana Sinovial/imunologia , Adulto , Idoso , Artrite Reumatoide/patologia , Linfócitos T CD4-Positivos/patologia , Feminino , Fibroblastos/imunologia , Humanos , Masculino , Pessoa de Meia-Idade , Membrana Sinovial/patologiaRESUMO
A hallmark of viral meningitis is the invasion of monocytes, lymphocytes and, in the initial phase of the disease, neutrophils into the subarachnoidal space. By their degradation of different macromolecular components in the extracellular connective tissue, matrix metalloproteinases (MMPs) may be essential for the breakdown of the vessel wall in the meninges and the choroid plexus. In this study, the occurrence of MMP-1, MMP-2, MMP-3 and MMP-9 and the two tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2, was monitored in the cerebrospinal fluid (CSF) from patients with viral meningitis. Of the proteinases, MMP-9 was found in 13 of 39 (33%) patients, but not in controls; the levels being correlated with the neutrophil cell number in CSF. The CSF concentration of TIMP-1 was increased three-fold compared to the control group (median 233 ng/ml; range 9.4-1252.5 ng/ml) and was correlated to the levels of total protein in CSF. Of the other MMPs and TIMPs assayed, MMP-2 and TIMP-2 were constitutively expressed and not upregulated in viral meningitis. High levels of MMP-9 and MMP-2, as measured by ELISA, was associated with high proteolytic activity detected in CSF by zymography. In conclusion, invasion of the leukocytes into the CSF compartment in viral meningitis may involve MMP-9, its proteolytic effect likely being controlled by expression of TIMP-1.
Assuntos
Colagenases/líquido cefalorraquidiano , Meningite Viral/enzimologia , Inibidor Tecidual de Metaloproteinase-1/líquido cefalorraquidiano , Adolescente , Criança , Ativação Enzimática/imunologia , Ensaio de Imunoadsorção Enzimática , Gelatinases/líquido cefalorraquidiano , Humanos , Linfócitos/enzimologia , Linfócitos/imunologia , Metaloproteinase 1 da Matriz , Metaloproteinase 2 da Matriz , Metaloproteinase 3 da Matriz/líquido cefalorraquidiano , Metaloproteinase 9 da Matriz , Meningite Viral/líquido cefalorraquidiano , Metaloendopeptidases/líquido cefalorraquidiano , Inibidores de Proteases/líquido cefalorraquidianoRESUMO
Human natural killer (NK) cells contain unique granules with parallel tubular arrays (PTA granules) of approximately 30 nm diameter that can be seen only by electron microscopy. In order to clarify the role of PTA granules in NK cell-mediated cytolysis we examined these structures with regard to frequency and expression of lytic proteins (perforin, granzymes). NK cells (CD3-, CD16+, CD56+) were obtained from heparinized blood of healthy donors and enriched by double-step negative selection using mAb coupled to magnetic beads. PTA granules were found in 31.3% of freshly separated NK cells. When NK cells were cultivated, even in the presence of various stimulating agents (rhIL-2, rhIL-4, rhIL-6, rhIL-12, GM-CSF, rhIFNalpha, anti-CD16 mAb, dexamethasone), PTA granules disappeared and transformed into conventional primary lysosomes. By immune electron microscopy using antibodies directed against perforin and granzyme B we observed distinct immuno-reactivity in the tubules and in the tubule-associated faintly electron-dense matrix of PTA granules. Immuno-labelling for perforin and granzyme B was also found in the fine granular matrix of primary lysosomes. Finally, we tested the distribution of chondroitin 4-sulfate which is suggested to inactivate lytic proteins. Immuno-reactivity for chondroitin 4-sulfate was detected only in the moderately electron-dense matrix but not in the tubules of PTA granules. These observations indicate that perforin and granzyme B are stored in an inactive form in PTA tubules due to highly ordered paracrystalline protein folding. As soon as the tubules decay the lytic proteins are kept in an environment of chondroitin 4-sulfate for inactivation.