Deciduosis of the appendix: diagnostic dilemma continues despite MRI evidence.

Deciduosis (ectopic or extrauterine decidua) is a phenomenon seen in the ovary and cervix and on serosal surfaces of abdominal and pelvic organs. It is thought to be the result of progesterone effects on extrauterine mesenchymal cells during pregnancy. Although deposits are typically asymptomatic and incidentally found in surgically removed tissues on microscopy, deciduosis has also been known to cause pain and intraperitoneal haemorrhage. We sourced all cases of appendiceal deciduosis that have occurred in Sir Charles Gairdner Hospital and Bunbury Hospital between the years 2006 and 2014. Clinical information was obtained from patients' medical records. Four cases of ectopic decidua of the appendix, all of which were incidentally found in pregnant patients presenting with features highly suggestive of appendicitis, were reviewed. These patients underwent appendicectomy and subsequent histopathology findings showed deciduosis with no evidence of appendicitis. Deciduosis of the appendix can mimic acute appendicitis in pregnancy. At present, it is difficult to confidently differentiate one from the other either by way of clinical presentation or with current imaging modalities.

Differential IL-12 responsiveness of T cells but not of NK cells from tumor-bearing mice in IL-12-responsive versus -unresponsive tumor models.

While IL-12 administration induces tumor regression through stimulating T cells in tumor-bearing mice, this IL-12 effect is observed in some but not all tumor models. The present study aimed to compare IL-12 responsiveness of T cells from tumor-bearing mice in IL-12-responsive (CSA1M and OV-HM) and -unresponsive (Meth A) tumor models. Tumor regression in IL-12-responsive tumor models required the participation of T cells, but not of NK1.1(+) cells. Because a NK1.1(+) cell population was the major producer of IFN-gamma, comparable levels of IFN-gamma production were induced in IL-12-responsive and -unresponsive tumor-bearing mice. This indicates that the amount of IFN-gamma produced in tumor-bearing individuals does not correlate with the anti-tumor efficacy of IL-12. In contrast, IL-12 responsiveness of T cells differed between the responsive and unresponsive models: purified T cells from CSA1M/OV-HM-bearing or Meth A-bearing mice exhibited high or low IL-12 responsiveness respectively, when evaluated by the amounts of IFN-gamma produced in response to IL-12. T cells from CSA1M- or OV-HM-bearing but not from Meth A-bearing mice exhibited enhanced levels of mRNA for the IL-12 receptor (IL-12R). These results indicate that a fundamental difference exists in IL-12 responsiveness of T cells between IL-12-responsive and -unresponsive tumor models, and that such a difference is associated with the expression of IL-12R on T cells.

B cell-mediated down-regulation of IFN-gamma and IL-12 production induced during anti-tumor immune responses in the tumor-bearing state.

Unfractionated spleen cells taken from tumor-bearing mice contained tumor-primed T cells which produced lymphokines such as IFN-gamma and IL-2 through collaboration with antigen-presenting cells (APC) binding tumor antigens when cultured in vitro. Here, we investigated the regulatory mechanisms underlying IFN-gamma production by T-APC interactions. Elimination of B cells from a splenic population of tumor-bearing mice resulted in enhanced IFN-gamma production. Adding B cells back into cultures down-regulated IFN-gamma production to almost the same levels as those induced by unfractionated spleen cells. IL-2 production was not enhanced by B cell depletion, but rather was significantly suppressed. IFN-gamma-selective up-regulation was due to an enhancement of IL-12 production because IL-12 was detected in B cell-depleted cultures and enhanced IFN-gamma production was prevented by addition of anti-IL-12 mAb or anti-CD40 ligand (CD40L) mAb capable of inhibiting CD40L-induced IL-12 production. These results indicate that B cells interfere with IFN-gamma production induced through interactions between anti-tumor T cells and APC, and this suppressive effect is based on the capacity of CD40+ B cells to down-regulate the CD40L-induced IL-12 production by APC.

Multiple roles of interferon-gamma in the mediation of interleukin 12-induced tumor regression.

Administration of recombinant interleukin 12 (IL-12) induces tumor regression that is associated with T-cell infiltration in the OV-HM ovarian carcinoma and CSA1M fibrosarcoma models. After confirming the blocking of regression by injection of anti-IFN-gamma monoclonal antibody (mAb), we investigated the mechanisms underlying the requirement of IFN-gamma in T-cell migration and tumor regression. T-cell migration was inhibited by injection of anti-IFN-gamma mAb to OV-HM tumor-bearing mice prior to IL-12 treatment. We examined, using the lymphoid cell migration assay, whether IFN-gamma is required for enhancing the migratory capacity of T cells or the T cell-accepting potential of tumor masses during IL-12 treatment. Spleen cells from IL-12-treated or untreated OV-HM-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into OV-HM-bearing mice that were not treated with IL-12. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses from recipient mice. Compared to spleen cells from OV-HM-bearing mice that were not treated with IL-12, enhanced migration was observed for cells from IL-12-treated OV-HM-bearing mice. Anti-IFN-gamma pretreatment of donor mice before IL-12 treatment did not reduce the migratory capacity of T cells, whereas migration was markedly inhibited in recipient mice injected with anti-IFN-gamma. Anti-IFN-gamma pretreatment decreased vascular cell adhesion molecule-1 (VCAM-1)-/intercellular adhesion molecule-1 (ICAM-1)-positive blood vessels at tumor sites. Consistent with this, migration was also inhibited by treatment of recipient mice with either anti-VCAM-1 or anti-ICAM-1 mAb. In contrast to the OV-HM model, T-cell migration was not affected in the CSA1M model following preinjection of anti-IFN-gamma mAb. In this model, VCAM-1-/ICAM-1-positive blood vessels existed even after anti-IFN-gamma treatment, although tumor regression was completely inhibited. These results indicate that IFN-gamma plays two distinct roles in expressing the antitumor efficacy of IL-12: one is to support the T-cell acceptability of tumor masses, and the other is to mediate the antitumor effects of migrated T cells.

Enhanced induction of antitumor T-cell responses by cytotoxic T lymphocyte-associated molecule-4 blockade: the effect is manifested only at the restricted tumor-bearing stages.

Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), a second counterreceptor for the B7 family of costimulatory molecules, functions as a negative regulator of T-cell activation. Here, we investigated whether the blockade of the CTLA-4 function leads to enhancement of antitumor T-cell responses at various stages of tumor growth. Unfractionated spleen cells taken from CSAIM fibrosarcoma-bearing mice 1-2 weeks after CSA1M cell implantation (early tumor-bearing mice) contained tumor-primed T cells that produced interleukin 2 and IFN-gamma through collaboration with antigen-presenting cell-binding tumor antigens when cultured in vitro. However, this initial lymphokine-producing capacity decreased at later stages of tumor growth (7-10 weeks after tumor cell implantation). Anti-CTLA-4 monoclonal antibody (mAb) was added to whole-spleen cell cultures from early or late tumor-bearing mice. Spleen cells from early tumor-bearing mice exhibited enhanced production of interleukin 2 and IFN-gamma upon in vitro culture in the presence of anti-CTLA-4 mAb. However, addition of anti-CTLA-4 mAb to whole-spleen cell cultures from late tumor-bearing mice failed to display such an enhancement. Consistent with these in vitro results, the in vivo antitumor effect of anti-CTLA-4 administration was observed in a tumor-bearing stage-restricted manner; in vivo administration of anti-CTLA-4 (1 mg/mouse, three times at 1-week intervals) into early tumor-bearing mice resulted in regression of growing tumors, whereas the same treatment did not affect tumor growth when performed for late tumor-bearing mice. Similar anti-CTLA-4 effect was observed in another tumor (OV-HM ovarian carcinoma) model. These in vitro and in vivo results indicate that CTLA-4 blockade in tumor-bearing individuals enhances the capacity to generate antitumor T-cell responses, but the expression of such an enhancing effect is restricted to early stages of tumor growth.

Enhanced induction of very late antigen 4/lymphocyte function-associated antigen 1-dependent T-cell migration to tumor sites following administration of interleukin 12.

Administration of interleukin 12 (IL-12) into mice bearing CSA1M, OV-HM, Meth A, or MCH-1-A1 tumor induced complete regression of CSA1M and OV-HM tumors but induced only a slight growth inhibition of Meth A and MCH-1-A1 tumors. These effects of IL-12 were associated with high and only marginal levels of T-cell infiltration into CSA1M/OV-HM and Meth A/MCH-1-A1 tumor masses, respectively. Here, we investigated the role of IL-12 in the induction of T-cell migration. Spleen cells from untreated or IL-12-treated CSA1M-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into IL-12-untreated CSA1M-bearing mice. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses. Although only a slight migration was detected for spleen cells from IL-12-untreated CSA1M-bearing as well as IL-12-treated or untreated normal mice, enhanced migration was observed for cells from IL-12-treated CSA1M-bearing mice. A similar enhanced migration was observed for the OV-HM model. In contrast, such an enhancement was only marginal in the Meth A and MCH-1-A1 models. Immunohistochemical studies of tumors from IL-12-treated mice revealed that the predominant T-cell subset was CD4+ in CSA1M and CD8+ in OV-HM tumor masses. Consistent with this observation, the dominant subset of migrating T cells was found to be CD4+ in the CSA1M and CD8+ in the OV-HM models. T-cell migration was inhibited by pretreatment of recipients with either combination of anti-very late antigen 4 + anti-vascular cell adhesion molecule 1 or anti-lymphocyte function-associated antigen 1 + anti-intercellular adhesion molecule 1 monoclonal antibody. These results indicate that IL-12 can confer T cells with a capacity to migrate to tumor sites through very late antigen 4/lymphocyte function-associated antigen 1 adhesion pathways and that the in vivo acquisition of such a capacity following IL-12 treatment correlates with the induction of tumor regression.

Molecular mechanisms underlying IFN-gamma-mediated tumor growth inhibition induced during tumor immunotherapy with rIL-12.

The present study investigates the molecular mechanisms by which IFN-gamma produced as a result of in vivo IL-12 administration exerts its anti-tumor effects. rIL-12 was administered three or five times into mice bearing CSA1M fibrosarcoma, OV-HM ovarian carcinoma or MCH-1-A1 fibrosarcoma. This regimen induced complete regression of CSA1M and OV-HM tumors but only transient growth inhibition of MCH-1-A1 tumors. The anti-tumor effects of IL-12 were associated with enhanced induction of IFN-gamma because these effects were abrogated by pretreatment of hosts with anti-IFN-gamma antibody. Exposure in vitro of the three types of tumor cells to rRFN-gamma resulted in moderate to potent inhibition of tumor cell growth. IFN-gamma stimulated the expression of mRNAs for an inducible type of NO synthase (iNOS) in CSA1M cells and indoleamine 2,3-dioxygenase (IDO), an enzyme capable of degrading tryptophan, in OH-HM cells, but induced only marginal levels of these mRNAs in MCH-1-A1 cells. In association with iNOS gene expression, IFN-gamma-stimulated CSA1M cells produced a large amount of NO which functioned to inhibit their own growth in vitro. Although OV-HM and MCH-1A1 cells did not produce NO, they also exhibited NO susceptibility. Whereas the tumor masses from IL-12-treated CSA1M-bearing or OV-HM-bearing mice induced higher levels of iNOS (for CSA1M) or IDO and iNOS (for OV-HM) mRNAs, the MCH-1-A1 tumor mass expressed lower levels of iNOS mRNA alone. Moreover, massive infiltration of CD4(+) and CD8(+) T cells and Mac-1(+) cells was seen only in the CSA1M and OV-HM tumors. Thus, these results indicate that IFN-gamma produced after IL-12 treatment induces the expression of various genes with potential to modulate tumor cell growth by acting directly on tumor cells or stimulating tumor-infiltrating lymphoid cells and that the effectiveness of IL-12 therapy is associated with the operation of these mechanisms.