Dendritic cells (DCs) are antigen-presenting cells with a unique ability to induce primary immune responses. DCs capture and transfer information from the outside world to the cells of the adaptive immune system. DCs are not only critical for the induction of primary immune responses, but may also be important for the induction of immunological tolerance, as well as for the regulation of the type of T cell-mediated immune response. Although our understanding of DC biology is still in its infancy, we are now beginning to use DC-based immunotherapy protocols to elicit immunity against cancer and infectious diseases.

Immunobiology of Dendritic Cells

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Interleukin-10 and the interleukin-10 receptor.

The innate immune system in drosophila and mammals senses the invasion of microorganisms using the family of Toll receptors, stimulation of which initiates a range of host defense mechanisms. In drosophila antimicrobial responses rely on two signaling pathways: the Toll pathway and the IMD pathway. In mammals there are at least 10 members of the Toll-like receptor (TLR) family that recognize specific components conserved among microorganisms. Activation of the TLRs leads not only to the induction of inflammatory responses but also to the development of antigen-specific adaptive immunity. The TLR-induced inflammatory response is dependent on a common signaling pathway that is mediated by the adaptor molecule MyD88. However, there is evidence for additional pathways that mediate TLR ligand-specific biological responses.

Toll-like receptors.

Recognition of pathogens is mediated by a set of germline-encoded receptors that are referred to as pattern-recognition receptors (PRRs). These receptors recognize conserved molecular patterns (pathogen-associated molecular patterns), which are shared by large groups of microorganisms. Toll-like receptors (TLRs) function as the PRRs in mammals and play an essential role in the recognition of microbial components. The TLRs may also recognize endogenous ligands induced during the inflammatory response. Similar cytoplasmic domains allow TLRs to use the same signaling molecules used by the interleukin 1 receptors (IL-1Rs): these include MyD88, IL-1R--associated protein kinase and tumor necrosis factor receptor--activated factor 6. However, evidence is accumulating that the signaling pathways associated with each TLR are not identical and may, therefore, result in different biological responses.

Toll-like receptors: critical proteins linking innate and acquired immunity.

Recognition of microbial infection and initiation of host defense responses is controlled by multiple mechanisms. Toll-like receptors (TLRs) have recently emerged as a key component of the innate immune system that detect microbial infection and trigger antimicrobial host defense responses. TLRs activate multiple steps in the inflammatory reactions that help to eliminate the invading pathogens and coordinate systemic defenses. In addition, TLRs control multiple dendritic cell functions and activate signals that are critically involved in the initiation of adaptive immune responses. Recent studies have provided important clues about the mechanisms of TLR-mediated control of adaptive immunity orchestrated by dendritic cell populations in distinct anatomical locations.

Toll-like receptor control of the adaptive immune responses.

Bispecific antibodies comprise two antigen-binding sites that recognize different antigens or epitopes. Blinatumomab, a bispecific T-cell engager (BiTE) that lacks the Fc portion, recognizes CD19 on B tumor cells and CD3 on T cells and induces the T cell-mediated killing of the B tumor cells. The Food and Drug Administration has approved the use of blinatumomab for the treatment of precursor B-cell acute lymphoblastic leukemia (ALL) with minimal residual disease and relapsed/refractory ALL. Various bispecific antibodies have been developed, including BiTEs that target surface molecules on myeloma cells or intracellular antigens presented on the major histocompatibility complex and Fc portion-containing bispecific antibodies that have a potent T cell-activating capacity and a long half-life. These efforts could lead to the development of potent, off-the-shelf bispecific antibodies for the treatment of a broad array of hematological malignancies.

Cancer therapy using bispecific antibodies

Recently, mepolizumab, an interleukin (IL)-5 inhibitor, has been indicated for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA) refractory to standard therapies However, no reports have compared the efficacy of mepolizumab according to symptoms and organ lesions Herein, we report two cases in which mepolizumab was highly effective in the management of EGPA with lung lesions and otitis media refractory to treatment with multiple immunosuppressive agents These two cases suggest that mepolizumab is effective in treating pulmonary and ear lesions in EGPA

Two cases of refractory eosinophilic granulomatosis with polyangiitis wherein mepolizumab was effective against pulmonary and ear lesions.

Fatal fulminant hemolysis-associated pulmonary embolism in mixed-type autoimmune hemolytic anemia: A case report.

We report a case of squamous cell lung cancer with transbronchial dissemination in a 73-year-old man. Bronchoscopic examination revealed multiple bronchial mucosal nodules that existed independently of one another. We reviewed 16 previous cases of endobronchial metastasis in lung cancer. All patients were men. Among the reports that described the smoking history, most patients were smokers (6/7), and the most frequent histological type of cancer was squamous cell carcinoma (11/17). Although hematogenous and lymphogenous routes have been reported as metastatic mechanisms, no previous cases involving transbronchial dissemination have been described. Transbronchial dissemination may be an alternative pathway of endobronchial metastasis.

https://journals.sagepub.com/doi/pdf/10.4137/CMO.S32707

Transbronchial Dissemination of Squamous Cell Lung Cancer.

Recombinant human thrombomodulin (rTM) improves the blood coagulation disorder characteristic of disseminated intravascular coagulation (DIC) as well as, or even better than, other anti-DIC drugs. On post-marketing surveillance, its effectiveness has been recognized for hematologic disorders, sepsis and solid tumor subgroups. However, the effect on hemophagocytic syndrome (HPS) complicated by DIC remains unclear. We treated three HPS patients with rTM in addition to chemotherapy for the underlying diseases including nasal NK/T cell lymphoma, angioimmunoblastic T-cell lymphoma and refractory acute myeloid leukemia post cord blood transplantation. Although being refractory to medical management was suspected in our cases, clinical status rapidly came under control including not only amelioration of the blood coagulation disorder but also inflammatory reactions, such as serum ferritin and lactic acid dehydrogenase abnormalities, which represent HPS activity. These observations suggest that rTM might exert marked synergistic effects on HPS with DIC. Given the results obtained in these three cases, administration of rTM appears to offer a promising method of treating HPS complicated by DIC.

Norimitsu Kadowaki

Papers

Cancer therapy using bispecific antibodies

Two cases of refractory eosinophilic granulomatosis with polyangiitis wherein mepolizumab was effective against pulmonary and ear lesions.

Fatal fulminant hemolysis-associated pulmonary embolism in mixed-type autoimmune hemolytic anemia: A case report.

Transbronchial Dissemination of Squamous Cell Lung Cancer.

Successful treatment with recombinant thrombomodulin for disseminated intravascular coagulation complicated with hemophagocytic syndrome