Pulling the plug on a pseudomonas outbreak: ancillary equipment as vectors of infection

OBJECTIVES

Outbreaks of infection related to flexible endoscopes are well described. However, flexible endoscopy also requires the use of ancillary equipment such as irrigation plugs. These are potential vectors of infection but are infrequently highlighted in the literature. This paper reports a cystoscopy-associated outbreak of Pseudomonas aeruginosa from contaminated irrigation plugs in a UK tertiary care centre.

METHODS

Laboratory, clinical and decontamination unit records were reviewed, and audits of the decontamination unit were performed. Flexible cystoscopes and irrigation plugs were assessed for contamination. Retrospective and prospective case finding was performed utilizing the microbiology laboratory information management system. Available P. aeruginosa isolates underwent variable nucleotide tandem repeat (VNTR) typing. Confirmed cases were defined as P. aeruginosa infection with an identical VNTR profile to an outbreak strain.

RESULTS

Three strains of P. aeruginosa were isolated from five irrigation plugs but none of the flexible cystoscopes. No acquired resistance mechanisms were detected. Fifteen confirmed infections occurred, including bacteraemia, septic arthritis and urinary tract infection. While failure of decontamination likely occurred because the plugs were not dismantled prior to reprocessing, the manufacturer's reprocessing instructions were also incompatible with standard UK practice. The Medicines and Healthcare Products Regulatory Agency was informed. A field safety notice was issued, and the manufacturer issued updated reprocessing instructions.

CONCLUSIONS

Ancillary equipment can represent an important vector for infection, and should be considered during outbreak investigations. Users should review the manufacturer's instructions for reprocessing ancillary equipment to ensure that they are compatible with available procedures.

Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty

This study explores how researchers' analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers' expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each team's workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers' results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.

Severing corneal nerves in one eye induces sympathetic loss of immune privilege and promotes rejection of future corneal allografts placed in either eye

Less than 10% of corneal allografts undergo rejection even though HLA matching is not performed. However, second corneal transplants experience a threefold increase in rejection, which is not due to prior sensitization to histocompatibility antigens shared by the first and second transplants since corneal grafts are selected at random without histocompatibility matching. Using a mouse model of penetrating keratoplasty, we found that 50% of the initial corneal transplants survived, yet 100% of the subsequent corneal allografts (unrelated to the first graft) placed in the opposite eye underwent rejection. The severing of corneal nerves that occurs during surgery induced substance P (SP) secretion in both eyes, which disabled T regulatory cells that are required for allograft survival. Administration of an SP antagonist restored immune privilege and promoted graft survival. Thus, corneal surgery produces a sympathetic response that permanently abolishes immune privilege of subsequent corneal allografts, even those placed in the opposite eye and expressing a completely different array of foreign histocompatibility antigens from the first corneal graft.

Allergic airway hyperreactivity increases the risk for corneal allograft rejection

Corneal allografts transplanted into hosts with allergic conjunctivitis experience an increased incidence and swifter tempo of immune rejection compared to corneal allografts transplanted to nonallergic hosts. Previous findings suggested that increased risk for rejection was not a local effect produced by an inflamed eye, but was due to perturbation of the systemic immune responses to alloantigens on the corneal allograft. We tested the hypothesis that another allergic disease, airway hyperreactivity (AHR), would also increase the risk for corneal allograft rejection. Induction of AHR with either ovalbumin (OVA) or short ragweed (SRW) extract prior to keratoplasty resulted in a steep increase in the speed and incidence of corneal allograft rejection. Delayed-type hypersensitivity (DTH) responses to corneal alloantigens were closely associated with corneal allograft rejection. However, the deleterious effect of AHR on corneal allograft survival was not reflected in a heightened magnitude of allospecific DTH, cytotoxic T lymphocyte and lymphoproliferative responses to the alloantigens on the corneal allograft. Unlike Th2-based immediate hypersensitivity, CD8+ T-cell-based contact hypersensitivity to oxazolone did not increase the risk for corneal allograft rejection. Thus, Th2-based allergic diseases significantly reduce the immune privilege of the corneal allograft and represent important risk factors for consideration in the atopic patient.

Differential roles of CD8+ and CD8- T lymphocytes in corneal allograft rejection in 'high-risk' hosts

We examined the role of perforin and FasL in corneal allograft rejection mediated by CD8+ and CD8 T cells. BALB/c corneas were transplanted orthotopically into vascularized, 'high-risk' graft beds in C57BL/6 mice, perforin knockout mice and FasL-defective gld/gld mice. CD8+ and CD8 T cells were collected following graft rejection and adoptively transferred to SCID mice, which were then challenged with BALB/c corneal allografts. In every case, CD8 T cells could mediate graft rejection when adoptively transferred to SCID mice that received BALB/c corneal allografts. Although CD8+ T cells also mediated graft rejection, the tempo was slower. Moreover, CD8+ T cells collected FasL-defective donors that had rejected corneal allografts, mediated corneal allograft rejection in only 50% of the SCID mice that received the adoptively transferred cells. In some cases, CD8+ T-cell-mediated rejection occurred in the absence of delayed-type hypersensitivity and cytotoxic T-lymphocyte activity, but was associated with CD8+ T-cell-mediated apoptosis of BALB/c corneal cells in vitro. The results demonstrate the redundancy in immune mechanisms of corneal allograft rejection. Either CD8+ or CD8 T cells can produce corneal allograft rejection, however functional FasL is necessary for optimal rejection, even in a high-risk setting.

Gamma delta T cells are needed for ocular immune privilege and corneal graft survival

It has been recognized for over a century that the anterior chamber of the eye is endowed with a remarkable immune privilege. One contributing component is the Ag-specific down-regulation of systemic delayed-type hypersensitivity (DTH) that is induced when Ags are introduced into the anterior chamber. This phenomenon, termed anterior chamber-associated immune deviation (ACAID), culminates in the generation of regulatory cells that inhibit the induction (afferent suppression) and expression (efferent suppression) of DTH. Since gamma delta T cells play a major role in other forms of immune regulation, we suspected they might contribute to the induction and expression of ACAID. Mice treated with anti-gamma delta Ab failed to develop ACAID following anterior chamber injection of either soluble Ag (OVA) or alloantigens (spleen cells). Additional experiments with knockout mice confirmed that mice lacking functional gamma delta T cells also fail to develop ACAID. Using a local adoptive transfer of DTH assay, we found that gamma delta T cells were required for the generation of regulatory T cells, but did not function as the efferent regulatory cells of ACAID. The importance of gamma delta T cells in corneal allograft survival was confirmed by blocking gamma delta T cells with GL3 Ab before corneal transplantation. While in vivo treatment with normal hamster serum had no effect on corneal graft survival, infusion of anti-gamma delta Ab resulted in a profound increase in corneal allograft rejection. Thus, gamma delta T cells are needed for sustaining at least one aspect of ocular immune privilege and for promoting corneal allograft survival.

Inhibition of intraocular tumor growth by topical application of the angiostatic steroid anecortave acetate

PURPOSE

This study examined the effect of an angiostatic agent on the growth of a highly vascularized intraocular tumor.

METHODS

A murine uveal melanoma cell line (99E1) was transplanted intracamerally into athymic nude BALB/c mice. Mice were treated topically three times per day beginning on the day of tumor transplantation and continuing through day 28. Groups included (a) 1% anecortave acetate, (b) vehicle control, or (c) no treatment. Tumor growth was scored clinically according to the volume of anterior chamber occupied by tumor. Intraocular tumor weights were determined on days 10, 14, 21, and 28. The effect of the test agents on tumor cell proliferation was examined in vitro by [3H]thymidine incorporation.

RESULTS

Tumors grew progressively in untreated mice and mice treated with the vehicle; tumors filled the entire eye by day 20 and frequently perforated the globe by day 21. By contrast, tumors treated with anecortave acetate grew significantly slower (P < 0.025) and did not perforate the eye. On days 21 and 28 the net tumor weight of the AL-3789-treated animals was 40% to 30% of controls (P < 0.05). Tumor inhibition was presumably due to the angiostatic properties of anecortave acetate because the compound did not affect tumor cell proliferation in vitro.

CONCLUSIONS

The topical ocular administration of anecortave acetate restricted the growth of a highly vascularized angiogenic intraocular tumor.

Conditions affecting enhanced corneal allograft survival by oral immunization

PURPOSE

To determine the optimal conditions for enhancing corneal allograft survival by oral immunization with donor-specific alloantigens.

METHODS

CB6F1 mice were orally immunized with various doses of C3H/Hej corneal epithelial and endothelial cells before receiving orthotopic C3H/Hej corneal allografts. Paraformaldehyde-fixed corneal cells were compared with viable corneal cells for their capacity to promote corneal allograft survival. The mucosal adjuvant, cholera toxin B (CTB), was examined for its capacity to enhance corneal graft survival when given separately or conjugated to corneal cells used for oral immunization. Oral immunization was also evaluated for its capacity to prevent immunologic rejection in three high-risk settings: preimmunized hosts, hosts with prevascularized graft beds, and grafts that contain donor-specific Langerhans' cells.

RESULTS

Optimal graft survival occurred when 2 x 10(6) corneal cells were administered orally 10 days before orthotopic corneal transplantation. Paraformaldehyde-fixed corneal cells were as effective as viable cells in preventing corneal graft rejection. Cholera toxin B enhanced the efficacy of oral immunization when conjugated with the orally administered corneal cells but was ineffectual when administered separately. Oral immunization with donor corneal cells enhanced corneal graft survival in all three high-risk settings.

CONCLUSIONS

Oral immunization with donor cells is an effective strategy for enhancing corneal graft survival and preventing graft rejection in high-risk settings. Graft enhancement is optimized when the orally administered cells are conjugated with CTB and administered before corneal transplantation. Because fixed cells retain their capacity to enhance corneal graft survival, it may be possible to store donor cells for long-term use in high-risk hosts.

Immunologic phenotype of hosts orally immunized with corneal alloantigens

PURPOSE

To evaluate the immunologic phenotype of hosts tolerized by oral administration of corneal alloantigens.

METHODS

CB6F1 mice were tolerized by oral administration of allogeneic C3H/Hej corneal epithelial and endothelial cells before receiving heterotopic C3H/Hej corneal allografts. C3H-specific cytotoxic T-lymphocyte (CTL), delayed-type hypersensitivity (DTH), and mixed-lymphocyte responses were evaluated in orally tolerized and control mice. Cytokine profiles of Peyer's patch cells from orally tolerized mice were determined by enzyme-linked immunosorbent assay and mink lung cell culture bioassay.

RESULTS

Oral administration of corneal cells produced a profound inhibition of allospecific CTL, DTH, and mixed-lymphocyte responses. Conjugation with the B subunit of cholera toxin markedly increased the tolerizing activity of corneal endothelial cells, so that a single dose of cholera toxin-conjugated corneal cells inhibited alloimmune responses to the same degree as 10 doses of corneal cells unconjugated with cholera toxin. Peyer's patch cells from orally tolerized mice produced reduced quantities of interferon-gamma and interleukin-2 but produced increased amounts of transforming growth factor-beta and interleukin-10 compared with concentrations in normal control animals.

CONCLUSIONS

Oral administration of cholera toxin-conjugated corneal cells produces a dose-dependent inhibition of allospecific CTL, DTH, and mixed-lymphocyte responses. Orally induced inhibition of cell-mediated immune responses to corneal alloantigens is correlated with a sharp increase in the secretion of transforming growth factor-beta and interleukin-10 and a concomitant suppression of interleukin-2 and interferon-gamma. The well-recognized immunosuppressive characteristics of transforming growth factor-beta and interleukin-10 are suggestive that orally induced tolerance to corneal alloantigens is mediated by these cytokines.

Oral immunisation as a strategy for enhancing corneal allograft survival

AIMS

To determine optimal conditions for enhancing corneal allograft survival through oral administration of donor specific corneal cells.

METHODS

A mouse model of penetrating keratoplasty was used to evaluate the efficacy and optimal conditions for preventing immunological rejection of corneal allografts. C3H corneal grafts were transplanted orthotopically to CB6F1 recipients and represented mismatches at the entire major histocompatibility complex (MHC) and multiple minor histocompatibility loci. Tissue cultured C3H corneal epithelial and endothelial cells were administered orally to CB6F1 mice before or shortly after the application of orthotopic C3H corneal allografts. Cultured C3H corneal cells were conjugated with the non-toxic B subunit of cholera toxin as a means of preferentially inducing oral tolerance.

RESULTS

Ten oral doses of donor cells administered before keratoplasty reduced the incidence of corneal graft rejection from 100% in untreated hosts to 54% in orally tolerised mice. Conjugation of cholera toxin to corneal cells significantly enhanced the efficacy of oral tolerance such that only 9% of the mice fed 10 doses of cholera toxin conjugated cells rejected their corneal grafts. Even a single oral inoculation of corneal cells conjugated to cholera toxin was able to reduce corneal graft rejection by 36%.

CONCLUSIONS

Oral administration of donor specific cells greatly enhances corneal graft survival. Use of cholera toxin adjuvant markedly enhances the efficacy of oral tolerance such that even a single oral dose of donor cells significantly reduces the incidence of rejection. The results support the clinical feasibility of this novel strategy for preventing immunological rejection of corneal transplants.

Anterior chamber-associated immune deviation promotes corneal allograft survival

PURPOSE

To determine whether anterior chamber-associated immune deviation (ACAID) promotes corneal allograft survival.

METHODS

CB6F1 mice were grafted with orthotopic corneal transplants from C3H donors (mismatch at the entire major histocompatibility complex plus multiple minor histocompatibility loci) and from NZB donors (mismatch only at multiple minor histocompatibility loci). ACAID was induced by priming in the anterior chamber (AC) with either Ia- spleen cells, Ia+ spleen cells, corneal endothelial cells, or corneal epithelial cells from corneal allograft donors before orthotopic transplantation. The role of ACAID in promoting corneal allograft survival was examined by determining the fate of corneal allografts in splenectomized and eusplenic mice.

RESULTS

Anterior chamber priming produced a modest enhancement of the survival of fully allogeneic C3H corneal allografts. By contrast, AC priming with Ia- NZB spleen cells or NZB corneal endothelial cells results in the permanent acceptance of NZB corneal grafts in 60% and 90% of the CB6F1 hosts, respectively. Abolition of ACAID by splenectomy resulted in a sharp increase in the incidence of graft rejection in donor-host combinations involving multiple minor histocompatibility disparity.

CONCLUSIONS

Anterior chamber priming with alloantigens promotes corneal allograft survival in nonimmune and preimmune hosts. Disruption of the camero-splenic axis prevents the induction of ACAID and greatly increases the risk for corneal allograft rejection.

The effect of oral immunization on corneal allograft survival

The present study examined the potential of orally induced tolerance for preventing immunological rejection of corneal allografts. Orthotopic corneal allografts were transplanted from either C3H (MHC + multiple minor H-mismatched) or NZB (multiple minor H-mismatched only) donors to CB6F1 recipients on day 0. Tissue cultured corneal epithelial and endothelial cells from relevant donor strains were administered orally from day -14 to day -4 on a daily basis, The incidence of graft rejection, graft mean survival time (MST), and alloimmune responses, and the antigen specificity of induced tolerance were studied. Oral immunization induced a remarkable tolerance such that only 55% of the orally immunized hosts rejected their fully allogeneic corneal grafts (MST = 43 days) compared with 100% rejection (MST = 18 days) in normal controls. Likewise, rejection of MHC-matched, multiple minor H-mismatched corneal grafts fell from 80% in untreated controls to 36% in orally immunized hosts. Oral immunization was effective in desensitizing previously immunized hosts. Rejection of MHC-matched, multiple H minor-mismatched corneal allografts fell from 93% in preimmune, unfed hosts to 36% in preimmune, orally tolerized mice. Thus, oral immunization is a safe and effective method for desensitizing high-risk, preimmune hosts and promoting corneal allograft survival.

Promotion of corneal allograft survival with leflunomide

PURPOSE

The efficacy of the antirejection drug leflunomide was evaluated in a rat model of penetrating keratoplasty.

METHODS

Corneal grafts from inbred Lewis rats were transplanted orthotopically to inbred Wistar-Furth (WF) recipients. WF rats received either Leflunomide (HWA 486), the active metabolite of leflunomide (A77-1726A), or cyclosporin A, administered orally beginning 2 days before transplantation and continuing for 30 days thereafter. Graft survival was assessed clinically three times per week, and mean survival times were determined.

RESULTS

Oral administration of either leflunomide or the salt of its active metabolite resulted in a significant prolongation of graft survival time. Moreover, almost one third of the grafts survived for an additional 3 weeks, even after drug treatment was discontinued.

CONCLUSION

The results indicate that leflunomide holds considerable promise as an antirejection drug for use in recipients of corneal transplants in whom cyclosporin A and steroids are contraindicated.

Effect of LFA-1 and ICAM-1 antibody treatment on murine corneal allograft survival

PURPOSE

To examine the effect of anti-LFA-1 and anti-ICAM-1 antibody treatment on orthotopic corneal graft survival in a mouse model.

METHODS

Anti-LFA-1 and anti-ICAM-1 antibodies were administered intraperitoneally before and shortly after orthotopic corneal transplantation. Grafts were observed by biomicroscopy, and survival times were determined. Cytotoxic T lymphocyte (CTL) and delayed-type hypersensitivity (DTH) responses to donor alloantigens were assessed at selected times after grafting.

RESULTS

Administration of anti-LFA-1 antibody reduced the incidence of graft rejection from 90% in untreated donors to 47% in anti-LFA-1 treated mice. By contrast, treatment with anti-ICAM-1 antibody alone did not reduce the incidence of rejection, although it prolonged graft survival time. Both CTL and DTH responses to donor alloantigens were severely depressed in hosts treated with either anti-LFA-1 or anti-ICAM-1 antibody. However, neither anti-ICAM-1 nor anti-LFA-1 antibody treatment prevented the rejection of orthotopic corneal grafts in previously immunized mice.

CONCLUSIONS

Anti-ICAM-1 antibody does not promote graft survival even though it impairs CTL and DTH responses to donor alloantigens. By contrast, anti-LFA-1 antibody can significantly reduce the incidence of orthotopic corneal graft rejection and prevent the induction of normal allospecific CTL and DTH responses. Although anti-LFA-1 antibody is effective if given prophylactically, it is ineffective at preventing corneal graft rejection in previously immunized hosts.

Capacity of simian virus 40 T antigen to induce self-tolerance but not immunological privilege in the anterior chamber of the eye

Transgenic mice bearing the simian virus 40 (SV40) large T oncogene developed progressively growing intraocular tumors and displayed characteristics of immunological tolerance to SV40 T antigen. Transgenic mice failed to mount CTL responses to SV40 T antigen-bearing tumor cell lines derived from the transgenic intraocular tumors. Spleen cells from transgenic hosts were able to prevent the in vivo and in vitro generation of CTL responses by lymphocytes from normal syngeneic FVB/N mice. Adoptive transfer of spleen cells from tolerant transgenic donors temporarily inhibited the immunological rejection of SV40 T antigen-positive tumor cells transplanted to normal syngeneic FVB/N recipients. Thus, introduction of SV40 transforming sequences into the mouse germline induced tolerance to SV40 T antigen. However, in normal FVB/N mice, SV40 T antigen-bearing tumor cells failed to experience immune privilege in the anterior chamber and did not elicit systemic down-regulation of delayed-type hypersensitivity responses that characteristically occur when antigens are introduced into the anterior chamber. The results indicate that within the anterior chamber of the eye, SV40 T antigen-bearing cells are perceived by the host's immune system much differently than are other categories of antigen. Thus, SV40 T antigen effectively induces self-immunological tolerance when its gene is introduced into the host's germline but fails to experience immunological privilege in the anterior chamber of the eye in normal hosts.

Effect of anti-ganglioside antibodies on the metastatic spread of intraocular melanomas in a nude mouse model of human uveal melanoma

In vivo and in vitro studies were performed to determine: (a) if human uveal melanoma cells expressed GD2 and GD3 gangliosides; (b) if anti-GD2 monoclonal antibodies would inhibit the propensity of human uveal melanoma cells to localize in the liver following intravenous injection; and (c) if anti-GD2 monoclonal antibody would reduce the spontaneous metastasis of primary intraocular melanomas in nude mice. The results showed that all three of the human uveal melanoma cell lines tested expressed GD2 and GD3 gangliosides in vitro and in vivo. The human uveal melanoma cell lines preferentially localized in the liver and entered the hepatic parenchyma following spontaneous metastasis from the eyes of nude mice. In vivo administration of anti-GD2 monoclonal antibody produced a sharp reduction in the number of uveal melanoma cells that disseminated to the liver following either intravenous injection or by spontaneous metastasis from primary intraocular melanomas. Collectively, the results demonstrate that uveal melanoma cells display a propensity to localize in the liver after entering the bloodstream; however, this localization can be significantly inhibited by in vivo administration of anti-ganglioside antibodies. The expression of GD2 and GD3 surface gangliosides on uveal melanomas and the capacity of anti-ganglioside antibodies to inhibit metastasis formation in mouse models of ocular and cutaneous melanomas raise the possibility of implementing anti-ganglioside antibodies as potential therapeutic agents for the management of uveal melanoma.

Functional characterization of mouse granulocytes and macrophages produced in vitro from bone marrow progenitors stimulated with interleukin 3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF)

Bone marrow from C3H/ouj mice was depleted to < 1% of CD11b+ granulocytes and macrophages using paramagnetic beads coated with sheep anti-rat antibodies. CD11b- cells, enriched three- to fourfold in colony-forming cells, were stimulated in liquid culture with interleukin 3 (IL-3) or granulocyte-macrophage colony-stimulating factor (GM-CSF). Cultures stimulated with IL-3 or GM-CSF increased cell numbers fourfold at 7 days, with the CD11b+ population increasing to 63% +/- 9% (n = 5) with IL-3 or 96% +/- 1% (n = 4) cells with GM-CSF. Functional responsiveness of the granulocytes and macrophages was assessed by flow cytometry in an oxidative burst assay using dichlorofluorescein (DCF) and a quantitative phagocytosis assay using opsonized fluorescent beads. Granulocytes and macrophages, identified by light scatter characteristics and allophycocyanine staining of CD11b, were assayed simultaneously with granulocytes from fresh mouse bone marrow and peripheral blood. GM-CSF-generated CD11b+ cells had higher oxidative responses than similar populations produced in response to IL-3. The oxidative burst of these in vitro generated CD11b+ populations was similar to the equivalent fresh bone marrow population. Oxidative burst responses of peripheral blood phagocytic cells could not be adequately measured in this system. Peripheral blood CD11b+ cells were the most phagocytic, followed by GM-CSF-stimulated CD11b+ cells; IL-3-stimulated and bone marrow CD11b+ cells were the least phagocytic. These data demonstrate that functional granulocytes can be produced in vitro using growth factors and that GM-CSF produces a more responsive cell than IL-3.

A pig model of Acanthamoeba keratitis: transmission via contaminated contact lenses

A model of contact lens-induced Acanthamoeba keratitis was developed in Yucatan micropigs. Pigs fitted with parasite-laden soft contact lenses developed corneal infections that clinically and histopathologically mimicked the human counterpart. Three distinct stages of disease became apparent and were categorized as: acute, condensed infiltrate, and resolution stages. Viable parasites were isolated from corneal scrapings and smears were taken during the acute and condensed infiltrate stages. In addition, cysts could be identified deep within the stroma of histological specimens taken during the resolution stages. The characteristic dense, white ring-like infiltrates, stroma edema, keratic precipitates, and the chronic nature of the infections were similar to those observed in human Acanthamoeba keratitis. Histopathological examination of infected corneas revealed extensive neutrophilic infiltrates, stromal necrosis, and disorganization of the collagen lamellae. The strong correlation between the clinical and histopathologic features of contact lens-induced Acanthamoeba keratitis in the pig as well as the anatomical similarity of the pig eye with the human eye make the porcine model a valuable tool for investigations of the immunology, cell biology, and therapy for Acanthamoeba keratitis.

The differential effects of donor versus host Langerhans cells in the rejection of MHC-matched corneal allografts

The fate of MHC-identical, multiple minor H-disparate corneal grafts was examined in the rat. Although skin grafts exchanged between LEW and F344 rats were invariably rejected, only 26% of the corresponding corneal grafts underwent rejection. The immunologic privilege of the minor H-disparate corneal grafts was due, at least in part, to the absence of donor-derived Langerhans cells. Corneal grafts were normally devoid of donor-derived Langerhans cells; however, grafts pretreated with latex beads became infiltrated with donor-derived Langerhans cells and were rejected by 59% of the naive minor H--compatible recipients. By contrast, untreated LEW corneal grafts underwent rejection in 26% of the naive F344 hosts even though the grafts became heavily infiltrated with host-derived Langerhans cells. The immunologic privilege of minor H-disparate corneal grafts was not the result of efferent blockade or suppression of the immune response. F344 hosts bearing long-term surviving LEW corneal allografts were challenged with LEW skin grafts. In all cases, orthotopic skin grafts were rejected acutely. Moreover, all previously clear corneal grafts underwent rejection following skin graft rejection. Thus, the unique absence of donor-derived Ia+ passenger cells and the avascular graft bed conspire to provide the primary minor H-disparate corneal graft with an immunologic privilege not shared by other organ grafts.

Converging evidence for identification of recurrent relationship themes: comparison of two methods

The therapeutic process is complex, and researchers and clinicians alike search for organizing principles or underlying structures that will reduce this complexity and thereby augment the efficacy of their respective endeavors. As other papers in this issue indicate, one such organizing principle is the concept of a recurring relationship theme that can be identified in the patient's descriptions of current and past relationships, as well as observed in the patient's interaction with the therapist. This concept has its origins in Freud's discovery of the transference phenomenon (1912), wherein the patient reenacts early relationships with significant others in the relationship with the analyst, and in Sullivan's interpersonal theory of psychiatry, with its central tenet that "personality is the relatively enduring pattern of recurrent interpersonal situations which characterize a human life" (1953, pp. 110-11). In the psychoanalytic and interpersonal therapies, these recurrent interpersonal themes, associated with the patient's difficulty in living and characterized as self-defeating and self-perpetuating, can potentially serve three main purposes: diagnosing and describing patients' difficulties, focusing therapeutic interventions, and measuring change on an individual basis. However, until recently, research on transference and rigidity of interpersonal style has been hampered by the lack of objective and clinically relevant measures for quantifying this clinical phenomenon (Kiesler 1986; Luborsky and Spence 1978). Luborsky (1977) developed the first reliable method for operationalizing the transference concept. Since then, as the companion papers in this issue point out, several different methods have been developed (e.g., Gill and Hoffman 1982; Horowitz 1979; Schacht et al. 1984). Although these methods differ in the postulated structural composition or components of the transference theme or recurrent relationship theme, they operate from similar methods of assessment. This paper presents the results of an initial investigation into convergent validity (Cronbach and Meehl 1955) of two of the major relationship theme methods--the Core Conflictual Relationship Theme (CCRT) of Luborsky and colleagues (Luborsky 1977), and the Cyclical Maladaptive Pattern (CMP: formerly called the "dynamic focus") of the Vanderbilt group (Schacht et al. 1984; Schacht and Henry, in press). In our investigation, developers of the approaches independently applied their methods to the same interview with a depressed patient. It was hypothesized that aside from differences due to the structural composition, the two methods would identify a similar relationship theme.

Phagocytosis of particulate antigens by corneal epithelial cells stimulates interleukin-1 secretion and migration of Langerhans cells into the central cornea

Under normal physiological conditions, the central corneal epithelium is devoid of Ia+ Langerhans cells. However, a variety of stimuli can induce the migration of peripheral Langerhans cells into the central regions of the cornea. In the present study, Langerhans cell migration was induced by the instillation of either sterile latex beads or formalin-killed Staphylococcus aureus into shallow incisions in the central corneal epithelium. Langerhans cells could be detected in the central cornea as early as 24 hours following instillation of either latex beads or S. aureus and remained for at least 6 weeks. Phagocytosis of latex beads by corneal epithelial cells was demonstrated in vivo and in vitro. Moreover, phagocytosis of latex beads stimulated corneal epithelial cells to secrete increased amounts of interleukin-1 (21-83% increase). The centripetal migration of peripheral corneal Langerhans cells in response to phagocytosis of latex beads could be mimicked by injecting as little as 0.001 units of human purified interleukin-1 (IL-1) into the central corneal epithelium. The IL-1 induced chemotaxis could be blocked by coinjection of anti-IL-1 antibody but not irrelevant antibody. The findings indicate that the exclusion of Langerhans cells from the central corneal epithelium is a dynamic process that can be regulated by the resident corneal epithelial cells themselves and raises the possibility that corneal epithelial cells and Langerhans cells collaborate in antigen processing within this organ.

Clinicians can agree in assessing relationship patterns in psychotherapy. The Core Conflictual Relationship Theme method

This study examines interjudge agreement on formulations of dynamic themes in psychotherapy, using a session-based method, namely, the Core Conflictual Relationship Theme. Agreement was assessed by two methods: one was based on themes that were tailor-made for each case, while the other was based on coding themes into a standard set of categories. To assess agreement on the tailor-made formulations, a paired-comparisons procedure was used. For a sample of 35 patients, the similarity ratings for matched cases were significantly higher than for purposely mismatched cases. Using the standard set of categories, agreement was also good; weighted kappa values ranged from .61 to .70. The results also demonstrate reliability for the location of the relationship episodes, which form the database for the Core Conflictual Relationship Theme. Our positive results suggest that this guided clinical method can be used reliably as a measure of relationship patterns in psychotherapy; our results provide the first moderate-sized sample demonstration of clinicians' agreement in formulating this complex concept.