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SummaryPrimary transcripts for all Ig heavy chain isotypes are alternatively processed to encode either secreted or membrane forms of the same antibody and, in plasma cells, a shift towards the secreted form occurs. In principle, measuring the relative quantities of secreted and membrane forms for a particular isotype could monitor B-cell plasmacytoid differentiation. Ratios of α heavy chain mRNA secreted (αs) to membrane (αm) form were assessed by quantitative reverse transcriptase–polymerase chain reaction (RT-PCR; TaqMan) using an IgA plasma cell line (NCI-H929), a surface IgA+ line (Dakiki) and human tonsillar B cells. While NCI-H929 cells showed the highest αs: αm ratio as expected, αs mRNA predominated for all unstimulated B cells and Dakiki cells. Treatment of B cells and Dakiki cells with IL-2 and IL-10 resulted in a further progression towards the αs form, correlating with increased human plasma cell antigen-1 (HPC1) mRNA levels. However, α mRNA processing and HPC1 expression were independently regulated, as IFN-γ treatment suppressed HPC1 levels while increasing αs: αm ratios. Cytokine-mediated increases in the αs: αm ratio resulted from strongly enhanced levels of αs with relatively constant αm values. Differentiation-related changes in mRNA processing can thus be tracked by automated quantitative PCR. [ABSTRACT FROM AUTHOR]

Sternoclavicular joint infections and osteomyelitis of the clavicle are extremely rare infections, especially in the pediatric population. Early signs of these infections are nonspecific and can be mistaken for common upper respiratory infections such as COVID-19 and influenza. Rapid diagnosis and treatment are critical for preventing potentially fatal complications such as mediastinitis. We present three cases of sternoclavicular joint infections in the past year during the COVID-19 pandemic. All three patients had delayed diagnoses likely secondary to COVID-19 workup. Each patient underwent surgical irrigation and débridement. Two of three patients required multiple surgeries and prolonged antibiotic courses. Placement of antibiotic-impregnated calcium sulfate beads into the surgical site cleared the infection in all cases where they were used. All three patients made a full recovery; however, the severity of their situations should not be overlooked. Children presenting to the hospital with chest pain, fever, and shortness of breath should not simply be discharged based on a negative COVID-19 test or other viral assays. A higher index of suspicion for bacterial infections such as clavicular osteomyelitis is important. Close attention must be placed on the physical examination to locate potential areas of concentrated pain, erythema, or swelling to prompt advanced imaging if necessary., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Although many immunotherapeutic investigations have focused on improving the effector limb of the antitumor response, few studies have addressed preventing the loss of tumor-associated Ag (TAA) expression, associated with immune escape by tumors. We found that TAA loss from human melanomas usually results from reversible gene down-regulation, rather than gene deletion or mutation. Previously, we showed that inhibitors of MAPK-signaling pathways up-regulate TAA expression in melanoma cell lines. We have now identified IFN-beta as an additional stimulus to TAA expression, including Melan-A/MART-1, gp100, and MAGE-A1. IFN-beta (but neither IFN-alpha nor IFN-gamma) augmented both protein and mRNA expression of melanocytic TAA in 15 melanoma lines (irrespective of initial Ag-expression levels). Treatment of low Ag melanoma lines with IFN-beta increased expression of melanocyte-lineage Ags, inducing susceptibility to lysis by specific CTLs. Treatment with IFN-beta also enhances expression of class I HLA molecules, thereby inducing both nominal TAA and the presenting HLA molecule. Data from fluorescent cellular reporter systems demonstrated that IFN-beta triggers promoter activation, resulting in augmentation of Ag expression. In addition to enhancing TAA expression in melanomas, IFN-beta also stimulated expression of the melanocytic Ag gp100 in cells of other neural crest-derived tumor lines (gliomas) and certain unrelated tumors. Because IFN-beta is already approved for human clinical use in other contexts, it may prove useful as a cotreatment for augmenting tumor Ag expression during immunotherapy.

We previously reported that antigen expression in melanoma cell lines is down-regulated by proteins secreted by antigen-negative melanoma cells. Here we report the purification and characterization of one of these down-regulatory factors, the cytokine, oncostatin M (OSM), which transmits its signal via the gp130 cell surface receptor, resulting in the selective down-modulation of the melanocyte lineage antigens: Melan-A/MART-1, gp100, tyrosinase, tyrosinase-related proteins 1 and 2, and the M isoform of microphthalmia transcription factor. Furthermore, we have found that some melanoma cell lines produce as yet uncharacterized factors distinct from OSM which also down-modulate antigen expression via signaling pathways different from that employed by OSM. These data indicate that there may be several regulatory pathways and molecules involved in the antigen-silencing process which may be related to the state of differentiation of the tumor cell and may affect the outcome of antitumor vaccine immunotherapies.

Interleukin 12 (IL-12) production is believed to be impaired in individuals with HIV infection and this impairment manifests early in disease, when the CD4(+) cell counts are within normal values. The reduced antigen-specific and mitogen-stimulated T cell-proliferative responses that occur in HIV infection can be corrected by the addition of recombinant human interleukin 12 (rhIL-12). As the IL-12 receptor (IL-12R) is central to the IL-12 signaling pathway, we examined whether the augmentation of antigen-specific proliferation of HIV(+) peripheral blood mononuclear cells (PBMCs) related to altered IL-12R expression. rhIL-12 augmented antigen-specific proliferation of HIV(+) PBMCs but not of HIV(-) PBMCs. Examination of resting PBMCs from HIV(+) and HIV(-) donors showed that neither of these populations expressed IL-12R beta 1 or IL-12R beta 2 chains on their cell surface as detected by flow cytometry. However, examination of mRNA showed that both IL-12R beta 1 and IL-12R beta 2 mRNAs were markedly reduced in HIV(+) PBMCs when compared with HIV(-) PBMCs. After mitogen activation there was an increase in IL-12R beta 1 expression on the cell surface of HIV(+) and HIV(-) PBMCs and this level was not altered by coculture with rhIL-12 or interferon gamma (IFN-gamma). However, coculture of phytohemagglutinin (PHA)-activated HIV(+) or HIV(-) PBMCs with rhIL-12 (but not IFN-gamma) increased IL-12R beta 2 expression on the cell surface of both populations. Examination at the message level showed a correction of IL-12R beta 1 to normal levels with activation that was further enhanced by rhIL-12 coculture for both the HIV(+) and HIV(-) PBMCs. However, although the level of IL-12R beta 2 for the HIV(+) PBMCs was normalized by PHA, rhIL-12 caused a further augmentation. This information provides a strong link between IL-12R upregulation, and the significant improvement in antigen-specific HIV-proliferative responses seen with the addition of rhIL-12. It also reveals that the dysfunction in IL-12R expression seen in cells from HIV(+) patients occurs at the transcriptional level. In addition, we provide further evidence that IL-12R beta 1 and IL-12R beta 2 regulation in human PBMCs is independent of IFN-gamma.