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Biomedical subjects

T H Ermak

Publications and source records attributed to T H Ermak.

At least 19 recordsLinked to original sources
PubMed1995

Uptake and transport of copolymer biodegradable microspheres by rabbit Peyer's patch M cells.

In this study, we demonstrate the role of M cells in uptake of poly(D-L-lactic-co-glycolic acid) (PLGA) microspheres and transport into rabbit Peyer's patches. Microspheres 1 to 10 microns in diameter composed of 50:50 lactic acid:glycolic acid were instilled into intestinal segments containing jejunal or ileal Peyer's patches, and uptake by M cells was examined by electron microscopy. PLGA microspheres visualized as electron-lucent, spherical particles were taken up by M cells by pseudopod-like extensions of the M cell apical membrane and translocated to the pocket region containing mononuclear leukocytes within 60 min. These results indicate that PLGA microspheres can be directed to M cell apical surfaces for delivery to immunocompetent cells in gut-associated lymphoid tissues.

Animals↗
PubMed1995

Oral immunization with recombinant Helicobacter pylori urease induces secretory IgA antibodies and protects mice from challenge with Helicobacter felis.

Helicobacter pylori, a gram-negative spiral bacterium, is the cause of chronic superficial (type B) gastritis and peptic ulcer disease. The urease enzyme of H. pylori was expressed as an inactive recombinant protein in Escherichia coli, purified as particulate structures of 550-600 kDa molecular mass with a diameter of approximately 12 nm. Given orally, 5 micrograms of urease with an appropriate mucosal adjuvant, such as the labile toxin of E. coli, protected 60%-100% of mice against challenge with virulent Helicobacter felis. Protection correlated with the level of secretory IgA antibodies against urease. Oral administration of antigen was as effective or better than intragastric administration. Parenteral injection of antigen or intragastric administration of high-dose antigen without adjuvant elicited serum IgG but no IgA antibodies and did not confer protection. Recombinant urease as an oral vaccine candidate deserves further investigation as an approach to the prevention of Helicobacter-induced chronic gastroduodenal diseases in humans.

Adjuvants, Immunologic↗
PubMed1994

Induction of autoimmune disease in mice by germline alteration of the T cell receptor gene expression.

Germline expression of rearranged TCR alpha-chain transgenes with the Ig H chain enhancer reproducibly elicits T cell-mediated autoimmune disease in the thyroid gland, gastric mucosa, Langerhans islets, salivary gland, ovaries, and testes in selected strains of normal mice. Multiple organs are destroyed in a single transgenic mouse and the same organ in transgenic strains with different MHC background, suggesting the transgene expression can elicit self-reactive T cell clones having different Ag specificities and MHC restrictions. Construction of this autoimmune-inducing TCR alpha EH transgene does not require particular V alpha J alpha gene segments or Ag specificities. Moreover, the autoimmune disease can be adoptively transferred to syngeneic normal mice by T cells expressing endogenous TCR alpha-chains. Taken together, these results indicate that the TCR alpha EH transgene expression does not suppress endogenous alpha-chain gene rearrangement and may trigger the expansion/activation of various self-reactive T cells expressing endogenous TCR alpha- and beta-chains. Furthermore, it appears that the transgene-induced autoimmune T cells are not deleted in the normal thymus or rendered anergic upon contact with the normal target self Ag, but can be controlled by a T cell-dependent mechanism, since transfer of the transgenic bone marrow cells to histocompatible SCID mice produces the same autoimmune disease as in the donors, and the autoimmune development in the SCID mice is effectively prevented by co-transfer of syngeneic nontransgenic T cells. This novel autoimmune model produced by genetic manipulation of the T cell lineage, not the target self Ag or the environment of T cell differentiation/selection, should be useful for elucidating the immunologic and genetic basis of autoimmune disease.

Age Factors↗
PubMed1992

Correlation of extracellular matrix components with the cytoarchitecture of mouse Peyer's patches.

The distribution patterns of extracellular matrix elements were determined to ascertain whether they play a role in the localization of lymphocytes in discrete T-cell, B-cell and dome antigen-processing domains within Peyer's patches. Antibodies against collagen types I, III and IV, laminin and fibronectin were applied to cryosections of mouse Peyer's patches and localized by direct or indirect immunoperoxidase methods. T-cell domains were identified with a monoclonal antibody against Thy-1.2. Labeled reticular fibers in distinctive patterns were more numerous in parafollicular and dome areas than within follicles. Germinal centers contained few such fibers. In parafollicular areas, fibers were oriented predominantly toward follicle domes; their distribution corresponded to T-cell zones and lymphocyte traffic areas, with their orientation being parallel to the migration pathways of lymphocytes from high endothelial venules to the antigen-processing domes. Subepithelial and subendothelial basal laminae were immunopositive for type-IV collagen, laminin and fibronectin. The dome subepithelial basal lamina had pore-like discontinuities through which lymphocytes migrated to and from the epithelium. The correspondence of the distribution patterns of extracellular matrix to specific functional domains of Peyer's patches suggests that this matrix provides a structural framework for lymphocyte migration and localization.

Animals↗
PubMed1991

Ultrastructural and cytoarchitectural features of lymphoreticular organs in the colon and rectum of adult BALB/c mice.

The structure and function of colonic mucosal lymphoid organs remain largely unexplored, especially in the rectum hidden within the pelvic vault. Two-month-old female BALB/c mice were anesthetized, and the entire colon was removed from cecum to anus. Distal colonic patches were then prepared for electron microscopy or were quick-frozen and sectioned for immunoperoxidase localization of B cells and T cell subsets. Aggregated lymphoid follicles were distributed irregularly along the entire colon with an average of 1.4 patches per centimeter of colon length. There were large collections of follicles opposite the ileocecal valve (cecal patches), variable numbers of patches throughout the colon, and at least one patch within 10 mm of the anus (rectal patch). Follicles were adjacent to branching crypts lined by epithelium infiltrated by lymphoid cells and containing few goblet cells. In electron micrographs, M cells were identified by their short, irregular microvilli; intraepithelial lymphoid cells; reduced lysosomal dense bodies; and an expanded tubulovesicular network. Small germinal centers were seen. Cytoarchitectural components of colonic lymphoid follicles and Peyer's patch follicles were remarkably similar, despite differences in surrounding mucosa and luminal microbial exposure. The presence of organized lymphoid tissue with M cells and germinal centers suggests that transepithelial particle transport and antigen recognition can take place in the rectum. Whether such tissue has the capacity for uptake of luminal microorganisms is of particular interest, not only because colonic follicles may be sites for local initiation of immune responses but also because they may be important entry points for systemic infection.

Animals↗
PubMed1991

Monoclonal antibody-directed targeting of fluorescent polystyrene microspheres to Peyer's patch M cells.

The ability to deliver particulates to Peyer's patch M cells for uptake into gut-associated lymphoid tissue was examined by administering simultaneously fluorescent green and red polystyrene microspheres into NZW rabbit intestinal loops containing Peyer's patches. Whereas green and red microspheres were taken up by M cells at equivalent concentrations (120 +/- 17 versus 125 +/- 18/mm length of dome), particles conjugated to the anti-M-cell monoclonal antibody 5B11 (IgM, kappa) were internalized by M cells 3-3.5 times more efficiently than conjugates displaying IgM of unrelated specificity (TEPC 183) or native particles of the reciprocal colour inoculated into the same loop at a comparable load. The microspheres formed a concentration gradient from lumen to subepithelial dome, and localized on M-cell apical membranes, M-cell pockets, and subepithelial domes. The transport rate across M cells of 5B11 or TEPC 183 conjugates was similar to that of untreated microspheres. These observations show that intestinal uptake into Peyer's patches can be upregulated by targeting M-cell luminal membrane structures.

Animals↗
PubMed1990

F(ab')2 anti-CD4 and intact anti-CD4 monoclonal antibodies inhibit the accumulation of CD4+ T cells, CD8+ T cells, and B cells in the kidneys of lupus-prone NZB/NZW mice.

Murine lupus in NZB/NZW (B/W) mice is characterized by immune-complex glomerulonephritis and lymphocytic infiltration of several organs, including the kidney. We recently showed that treatment of B/W mice with F(ab')2 anti-CD4 monoclonal antibody retards autoimmunity by inhibiting the function of CD4+ cells and not by depleting them. To determine if treatment with F(ab')2 anti-CD4 prevented lymphocytic infiltration of kidneys or simply inhibited the function of the infiltrating lymphocytes, long-term survivors of treatment with F(ab')2 anti-CD4 and intact anti-CD4 were sacrificed for immunohistochemical analysis of their kidneys. Untreated B/W mice had large lymphocytic aggregates under the surface epithelium of the renal calyces. Most of these lymphocytes were CD4+ T cells, but CD8+ T cells and B cells were also present. In contrast, treatment with either intact anti-CD4 or F(ab')2 anti-CD4 substantially reduced, and in many cases prevented, the development of renal infiltrates. Treatment with either form of anti-CD4 not only inhibited renal infiltration by CD4+ T cells, but also prevented the accumulation of CD8+ T cells and B cells. These observations suggest a role for the CD4+ T cell in the accumulation of lymphocytes in target organs.

Animals↗
PubMed1990

Intrathymic changes in murine CD3, CD5 and CD8 expression after in vivo administration of anti-CD4.

Intrathymic development of murine cortical and medullary thymocyte subpopulations was examined after in vivo administration of anti-CD4 mAb. Four days after mice received 1 mg anti-CD4, expression of CD4 was reduced to about 25% the levels of controls. On cortical CD8+/PNAhigh thymocytes, CD5 and CD8 expression both decreased, but not in parallel, whereas CD3 expression increased almost 2-fold. Partial shifts in CD3 expression were seen 3 and 6 h after injection, but modulation of CD4 preceded the increase in CD3 expression. On medullary CD8-/PNAlow thymocytes, both CD3 and CD5 were down regulated. On nontargeted CD8+/PNAlow medullary thymocytes, expression of these molecules was decreased less than 20%, but the decrease in CD8 expression was primarily due to the appearance of a CD8low subpopulation. The results indicate that anti-CD4 mAb differentially affects the intrathymic development of T cell populations.

Animals↗
PubMed1990

A new model of Pneumocystis carinii infection in mice selectively depleted of helper T lymphocytes.

Pulmonary infections with Pneumocystis carinii are an important cause of morbidity and mortality in patients with AIDS. P. carinii infections are seen in patients with decreased numbers of helper T lymphocytes, suggesting that these cells are important in preventing infection. To test this hypothesis, we sought to establish experimental infection with P. carinii in mice selectively depleted of helper T lymphocytes. Weekly injections of a monoclonal anti-CD4 antibody produced sustained depletion of helper T lymphocytes from blood and lymphoid organs. To establish pulmonary infection, lymphocyte-depleted mice were then given intratracheal inoculations of P. carinii organisms derived from the lungs of chronically infected athymic mice. Pulmonary infection with P. carinii was demonstrable in the antibody-treated mice and was centered around the conducting airways. Infection was persistent for up to 3 mo with continued antibody treatments, and yet could be cleared from the lungs if antibody treatments were discontinued. This experimental model of P. carinii infection permits the study of infection associated with a specific immune defect and implicates the helper T lymphocyte as a critical cell in host defense against this pathogen.

Animals↗
PubMed1990

Phenotypically distinct subpopulations of T cells in domes and M-cell pockets of rabbit gut-associated lymphoid tissues.

Follicle epithelium and domes of gut-associated lymphoid tissue (GALT) contain populations of lymphocytes which first contact antigen taken up from the intestine. In order to study the association of lymphocytes with M cells in follicle epithelium, monoclonal antibodies (mAb) were generated by immunizing BALB/c mice with lymphocytes populating GALT domes from NZW rabbits, and their specificity was assessed by immunohistochemistry and flow cytometry. mAb 3C10 (IgM) and 3B6 (IgG3) recognized subpopulations of intraepithelial lymphocytes associated with M cells. mAb 3C10 also identified macrophage-lymphocyte clusters in domes and tangible body macrophages in germinal centres of GALT but did not react with cells in T-dependent areas (TDA) or B cells in follicles. mAb 3B6 recognized lymphocytes in domes and B cells in follicles but not T cells in TDA of GALT. The distribution of 3B6+ cells overlapped with, but was more restricted than, that of Ia+ cells. Analysis of lymphocytes in follicle epithelium showed that greater than 95% of lymphocytes associated with M cells were Ia+. T cells represented approximately 95% of intraepithelial lymphocytes in the appendix and approximately 65% in Peyer's patches. A majority of intraepithelial lymphocytes was recognized by mAb 3B6, but mAb 3C10 identified only approximately 30%. Because neither 3C10 nor 3B6 recognized lymphocytes in TDA of GALT, these results indicate that most lymphocytes associated with M cells are a distinct phenotype of Ia+ T cells.

Animals↗
PubMed1989

Treatment of murine lupus with monoclonal antibody to L3T4. II. Effects on immunohistopathology of thymus, spleen, and lymph node.

Monoclonal antibody to L3T4 has been used successfully to suppress autoimmunity in the New Zealand black/New Zealand white F1 (B/W) mouse model for systemic lupus erythematosus. To clarify the immunopathology of murine lupus and determine the effects of anti-L3T4 treatment on the cellular composition and histopathology of lymphoid organs, we examined the distribution of lymphocyte subsets in cryostat sections of the thymus, spleen, and lymph nodes of B/W mice. Immunohistologic specimens were obtained from female B/W mice that had received weekly intraperitoneal injections of either rat monoclonal antibody to L3T4 (2 mg/mouse/week) or phosphate buffered saline (200 microliters/mouse/week) from age 5 months until euthanasia at 8 months. B and T cell domains in each organ were identified on serial sections with monoclonal antibody directed against B220 (all B cells), Thy-1.2 (all T cells), L3T4 (helper T cells), and Ly-2 (cytotoxic/suppressor T cells). In control mice, striking cytoarchitectural abnormalities were identified in the thymuses, and the spleen and lymph nodes were hypertrophied relative to anti-L3T4 treated mice. Thymic abnormalities included amplification of medulla, formation of thymomas, and cortical atrophy. Amplified medullary regions and thymomas in B/W mice contained numerous B cells and L3T4+ T cells but few Ly-2+ T cells. The enlarged spleens and lymph nodes of control mice consisted of numerous secondary follicles with germinal centers containing an unusual subpopulation of T cells that expressed L3T4 but not Thy-1.2. In contrast, mice treated with anti-L3T4 did not develop histopathologic changes characteristic of systemic lupus erythematosus in any organ. However, treatment depleted L3T4+ cells from the spleen and lymph nodes, and it modulated the expression of L3T4 by thymocytes. These observations demonstrate that treatment with anti-L3T4 not only interferes with L3T4-dependent T cell functions, but it also prevents progressive abnormalities in lymphoid tissue in lupus-prone B/W mice. This preservation of normal lymphoid structure may contribute to the beneficial effects of anti-L3T4 on autoimmunity.

Animals↗
PubMed1989

Uptake and translocation of fluorescent latex particles by rabbit Peyer's patch follicle epithelium: a quantitative model for M cell uptake.

A quantitative, light microscopic morphometric model for uptake of particulates by Peyer's patch M cells was developed. Rabbit intestinal loops containing Peyer's patches were inoculated with fluorescent, non-degradable polystyrene microparticles (600-750 nm), and their localization in Peyer's patches was traced after varying time periods. The particles were localized sequentially at the FAE cell surface, spanning the entire width of FAE cells, and within the subepithelial dome as a function of time. The particles were associated with 5D9+ or 1D9+ M cells, but were not taken up or transported by villus epithelia. The kinetics suggested a synchronous wave of uptake and transepithelial transport. Quantitative analysis revealed a considerably greater uptake efficiency of polystyrene microspheres in comparison to other biological particles.

Animals↗
PubMed1989

M cells and granular mononuclear cells in Peyer's patch domes of mice depleted of their lymphocytes by total lymphoid irradiation.

The cytoarchitecture of Peyer's patches that were depleted of their lymphocytes by total lymphoid irradiation (TLI) was examined with particular attention to the effects on M cells in the follicle epithelium and on mononuclear cells in follicle domes underlying the epithelium. Five-month-old, specific pathogen-free Balb/c mice were irradiated with 200-250 rad/day, five times a week to a total dose of 3400-4250, and their Peyer's patches were either fixed for electron microscopy or frozen for immunohistochemistry 1-4 days after completion of irradiation. Control mice were examined at the same time intervals. Follicle domes of TLI mice had approximately one fourth the epithelial surface area of domes of control mice. Within the epithelium, lymphoid cells were virtually depleted after TLI, and yet the epithelium contained M cells. In control mice, most M cells were accompanied by lymphoid cells in invaginations of the apical-lateral cell membrane. In TLI mice, most M cells did not have such apical-lateral invaginations and were columnar shaped. Other than lacking lymphocytes, these cells appeared to be mature M cells. Some M cells did have lymphoid cells or granular mononuclear cells below their basal membranes, adjacent to the basal lamina. Below the epithelium, the proportion of granular mononuclear cells was greatly increased following TLI. The retention of M cells and the increase in proportion of granular mononuclear cells in follicle domes are consistent with selective depletion of lymphocytes following TLI. Persistence of M cells without lymphocytic invaginations after TLI suggests that M cells can differentiate in the absence of, or at least in the presence of very few, lymphocytes, and that invagination by lymphocytes is not necessary to maintain mature M cell morphology.

Animals↗
PubMed1988

CD4-/CD8-T cells: amplification in spleens of mice following in vivo treatment with monoclonal antibody anti-L3T4.

Amplification of L3T4-/Ly-2-(CD 4-/CD 8-) T cells following in vivo administration of anti-L3T4 monoclonal antibody was examined in the spleen of mice by flow cytometry and immunohistochemistry. BALB/c mice were given 4-7 weekly injections of either anti-L3T4 (1 mg/week) or phosphate-buffered saline (control group), and dispersed spleen cells and tissue sections analyzed for the presence of Thy-1.2+, L3T4+, or Ly-2+ cells, and for the absence of both L3T4 and Ly-2 on Thy-1.2+ cells. Prior to treatment, L3T4+ and Ly-2+ cells accounted for virtually all Thy-1.2+ cells in approximately a 2:1 ratio. Following anti-L3T4 treatment, L3T4+ cells were depleted, and Ly-2+ cells accounted for about 2/3 of the Thy-1.2+ cells. A population of L3T4-/Ly-2- T cells was generated that accounted for 20-30% of the Thy-1.2+ cells, accounted for most of the Thy-1.2+ cells in red pulp, and was also present among the predominant Ly-2+ cells in periarteriolar sheaths.

Animals↗
PubMed1988

Generation of L3T4-/Ly-2- T cells in Peyer's patches of mice treated with monoclonal antibody against helper T cells.

The effect of in vivo administration of anti-L3T4 monoclonal antibody on the generation of an L3T4-/Ly-2- (CD4-/CD8-) population of Thy-1.2+ cells was examined in Peyer's patches of mice by two-color flow cytometry. Female BALB/c mice aged 8 wk were given 4-6 weekly injections of either anti-L3T4 (1 mg/wk) or phosphate-buffered saline (control group), and dispersed Peyer's patch cells analyzed for the presence and absence of L3T4 and Ly-2 on Thy-1.2+ cells. In anti-L3T4 treated mice, L3T4-/Ly-2- T cells accounted for 25-30% of the Thy-1.2+ cells, whereas in control mice these cells represented only 3-4% of the T cells. The remaining 70-75% of the Thy-1.2+ cells after anti-L3T4 treatment were Ly-2+ and not L3T4+. The L3T4-/Ly-2- population of Thy-1.2+ cells is a novel subset which has not been previously found in Peyer's patches and is amplified when helper T cells are depleted.

Animals↗
PubMed1988

Treatment of murine lupus with monoclonal antibody to L3T4. I. Effects on the distribution and function of lymphocyte subsets and on the histopathology of autoimmune disease.

Monoclonal antibodies (MoAb) to L3T4 have been used successfully to suppress autoimmunity in murine models for several human autoimmune diseases. To clarify the immunologic and clinical consequences of treatment with anti-L3T4, we examined the effects of chronic administration of anti-L3T4 on the composition of lymphoid organs, the function of lymphocytes, and the histopathology of autoimmune disease in lupus-prone NZB/NZW F1 (B/W) mice. Weekly treatment with anti-L3T4 (2 mg/mouse) from age 5 to 8 months depleted L3T4+ cells from the spleen and lymph nodes, and prevented the development of splenomegaly and lymphadenopathy. The MoAb bound to target cells in the thymus and modulated their expression of the L3T4 antigen but, in contrast to its effect in extrathymic sites, anti-L3T4 did not deplete the target population from the thymus. In fact, after 3 months of therapy, mice that had been treated with anti-L3T4 had much larger thymuses than control mice that had been treated with saline, suggesting that treatment with anti-L3T4 prevented the thymic atrophy that occurs spontaneously in murine lupus. Despite depleting L3T4+ cells from the spleen, treatment with anti-L3T4 did not diminish the response of splenic lymphocytes to T and B cell mitogens, and it augmented splenic natural killer (NK) cell activity. Finally, treatment with anti-L3T4 decreased the diverse histopathologic manifestations of murine lupus. It dramatically reduced glomerular immunoglobulin and complement deposition and diminished lymphocytic infiltration and vasculitis in the kidneys. Treatment also reduced extrarenal immunopathology, including focal hepatitis and salivary gland infiltration. These observations have implications regarding the use of CD4 MoAb in people with autoimmune diseases.

Animals↗