MUM1/IRF4: A Review. Appl Immunohistochem Mol Morphol. 2010;18:301-310. [PMID: 20182347 DOI: 10.1097/pai.0b013e3181cf1126]

Expression of IRF-4 and IBP in skin lesions of patients with psoriasis vulgaris

The expression of the interferon regulatory factor 4 (IRF-4) and the IRF-4-binding protein (IBP) in psoriatic skin lesions was investigated. The expression of IRF-4 and IBP in skin lesions of 20 patients with psoriasis vulgaris were immunohistochemically dectected. Normal skin from 10 healthy people was used as normal control. The study showed that expression of IRF-4 was increased significantly in keratinocytes and inflammatory cells in the lesions of psoriasis vulgaris than that in the normal control. The detection revealed that IBP expression in keratinocytes, lymphocytes, hair follicles, and sebaceous glands in normal skin was significantly lower than that in the lesions of psoriasis vulgaris (P<0.05). Both IRF-4 and IBP might be involved in the pathogenesis of psoriasis vulgaris.

Aberrant antigenic expression in extranodal NK/T-cell lymphoma: a multi-parameter study from Thailand

Background

Extranodal NK/T-cell lymphoma, nasal type (ENKTL) is not common worldwide, but it is the most common T- and NK-cell lymphomas in many Asian countries. Immunophenotypic profiles were studied based on limited series. The authors, therefore, studied on ENKTL according to characterize immunophenotypic profiles as well as the distribution of EBV subtype and LMP-1 gene deletion.

Methods

By using tissue microarray (TMA), immunohistochemical study and EBV encoded RNA (EBER) in situ hybridization were performed. T-cell receptor (TCR) gene rearrangement, EBV subtyping, and LMP-1 gene deletion were studied on the available cases.

Results

There were 22 cases eligible for TMA. ENKTL were positive for CD3 (91%), CD5 (9%), CD7 (32%), CD4 (14%), CD56 (82%), TIA-1 (100%), granzyme B (95%), perforin (86%), CD45 (83%), CD30 (75%), Oct2 (25%), and IRF4/MUM1 (33%). None of them was positive for βF1, CD8, or CD57. TCR gene rearrangement was negative in all 18 tested cases. EBV was subtype A in all 15 tested cases, with 87% deleted LMP-1 gene. Cases lacking perforin expression demonstrated a significantly poorer survival outcome (p = 0.008).

Conclusions

The present study demonstrated TIA-1 and EBER as the two most sensitive markers. There were a few CD3 and/or CD56 negative cases noted. Interestingly, losses of CD45 and/or CD7 were not uncommon while Oct2 and IRF4/MUM1 could be positive in a subset of cases. Based on the present study in conjunction with the literature review, determination of PCR-based TCR gene rearrangement analysis might not be a useful technique for making diagnosis of ENKTL.

The role of CD40/CD40L and interferon regulatory factor 4 in Hodgkin lymphoma microenvironment

Inflammation and cancer are two independent biological events that can play an interdependent role. The model of such interaction is represented by Hodgkin lymphoma (HL), where the microenvironment is dominated by an extensive mixed, potentially cellular inflammatory infiltrate that plays a decisive role in the pathobiology of HL. In this review we summarize updated information on the complex interactions between Hodgkin Reed-Sternberg (HRS) cells and their tissue microenvironment, highlighting the functional role of CD40/CD40L and interferon regulatory factor 4 (IRF4).

IRF4 silencing inhibits Hodgkin lymphoma cell proliferation, survival and CCL5 secretion

Interferon regulatory factor 4 (IRF4) expression is detected in many lymphoid and myeloid malignancies, and may be a promising therapeutic target. IRF4 is strongly expressed in classical Hodgkin lymphoma (cHL) and its expression is up-regulated by CD40L and down-regulated by both anti-proliferative and pro-apoptotic stimuli. This study analysed the effects of IRF4 silencing in a panel of HL-derived cell lines. We demonstrated that IRF4 down-modulation determined a remarkable decrease of both cell number and clonogenic growth in L-1236, L-428, KM-H2 and HDLM-2 cells, but not in IRF4-negative L-540 cells. IRF4 silencing induced apoptosis, as evaluated by caspase-3 activation and Annexin-V staining and up-regulation of the pro-apoptotic molecule Bax. CD40 engagement by both soluble and membrane bound-CD40L almost totally reduced IRF4 down-modulation and growth inhibition by IRF4 silencing in both L-1236 and L-428 cells. Finally, IRF4 silencing decreased CCL5 secretion in all HL cell lines tested and CCL17 in KM-H2 cells. Taken together, our results demonstrated that IRF4 down-modulation by IRF4 silencing was reversed by CD40 engagement, inhibited HL cells proliferation, induced apoptosis and decreased CCL5 secretion, thus suggesting that IRF4 may be involved in HL pathobiology.