Umbilical cord blood (UCB) has advantages over other tissues because it can be obtained without an invasive procedure and complex processing. We explored the availability of cryopreserved UCB cells as a source of mesenchymal stromal/stem cells (MSCs). MSCs were successfully isolated from six of 30 UCB units (median volume, 34.0 mL; median nucleated cell number, 4.4×10⁸) that were processed and cryopreserved using CP-1/human serum albumin. This isolation rate was lower than that (57%) from non-cryopreserved UCB cells. The number of nucleated cells before and after hydroxyethyl starch separation, UCB unit volume, and cell viability after thawing did not significantly differ between UCB units from which MSCs were successfully isolated and those from which they were not. When CryoSure-DEX40 was used as a cryoprotectant, MSCs were isolated from two of ten UCB units. Logistic regression analysis demonstrated that the cryopreservation method was not significantly associated with the success of MSC isolation. The isolated MSCs had a similar morphology and surface marker expression profile as bone marrow-derived MSCs and were able to differentiate into osteogenic, adipogenic, and chondrogenic cells. In summary, MSCs can be isolated from cryopreserved UCB cells. However, the cryopreservation process reduces the isolation rate; therefore, freshly donated UCB cells are preferable for the isolation of MSCs.

Growing adult T-cell leukemia/lymphoma (ATLL) cells in vitro is difficult. Here, we examined the effects of static electricity in the culture medium on the proliferation of ATLL cells. Six out of 10 ATLL cells did not proliferate in vitro and thus had to be cultured in a medium containing negatively charged polymers. In the presence of poly-γ-glutamic acid (PGA) or chondroitin sulfate (CDR), cell lines (HKOX3-PGA, HKOX3-CDR) were established from the same single ATLL case using interleukin (IL)-2, IL-4, and feeder cells expressing OX40L (OX40L⁺HK). Dextran sulfate inhibited growth in both HKOX3 cell lines. Both PGA and OX40L⁺HK were indispensable for HKOX3-PGA growth, but HKOX3-CDR could proliferate in the presence of CDR or OX40L⁺HK alone. Thus, the specific action of each negatively charged polymer promoted the growth of specific ATLL cells in vitro.

Cell adhesion molecule 1 (CADM1) is a cell adhesion molecule that is expressed in brain, liver, lung, testis, and some kinds of cancer cells including adult T-cell leukemia/lymphoma (ATLL). Recent studies have indicated the involvement of CADM1 in cell-cell contact between cytotoxic T-lymphocytes and virus infected cells. We previously reported that cell-cell interaction between lymphoma cells and macrophages induces lymphoma cell proliferation. In the present study, we investigated whether CADM1 is associated with cell-cell interaction between several human lymphoma cell lines and macrophages.

CADM1 expression was observed in the ATLL cell lines, ATN-1, ATL-T, and ATL-35T, and in the B cell lymphoma cell lines, TL-1, DAUDI, and SLVL, using western blotting. Significant cell-cell interaction between macrophages and ATN-1, ATL-T, ATL-35T and MT-2, DAUDI, and SLVL cells, as assessed by induction of cell proliferation, was observed. Immunohistochemical analysis of human biopsy samples indicated CADM1 expression in 10 of 14 ATLL cases; however, no case of follicular lymphoma or diffuse large B-cell lymphoma was positive for CADM1. Finally, the interaction of macrophages with cells of the CADM1-negative ED ATLL cell line and CADM1-transfected ED cells was tested. However, significant cell-cell interaction between macrophage and CADM1-transfected ED cells was not observed. We conclude that CADM1 was not associated with cell-cell interaction between lymphoma cells and macrophages, although CADM1 may be a useful marker of ATLL for diagnostic procedures.

Recent studies have indicated the significance of immune checkpoint molecules including programmed death-1 (PD-1), cytotoxic T-lymphocyte associated protein 4, and T-cell immunoglobulin and mucin domain-containing molecule-3 for anti-tumor immune responses. We previously investigated PD-1 ligand 1/2 (PD-L1/2) expression in lymphoma cell lines, and found that PD-L1/2 is expressed on the adult T-cell leukemia/lymphoma (ATL-T) and B-cell lymphoma (SLVL) cell lines. In the present study, we investigated whether the Stat3 inhibitor WP1066 abrogated PD-L1/2 expression in lymphoma cell lines. Incubation with WP1066 inhibited lymphoma cell growth and induced cell apoptosis. PD-L1/2 expression in the ATL-T, SLVL, and human brain malignant lymphoma (HKBML) cell lines was significantly abrogated by WP1066 treatment. These data indicated that a Stat3 inhibitor abrogated PD-L1/2 expression in lymphoma cells. Such an inhibitor is therefore considered to be useful for additional immunotherapy in patients with advanced lymphoma.

Cryptococcosis is an invasive fungal infection in immunocompromised patients. The clinicopathological characteristics of cryptococcal lymphadenitis are not well known. We analyzed three cases of cryptococcal lymphadenitis and compared their characteristics with those in previous reports. Two patients were human immunodeficiency virus (HIV) carriers, and one patient was a human T-cell leukemia virus type-1 (HTLV-1) carrier. The age of the HTLV-1 carrier with cryptococcosis was much higher than that of the HIV-1 carriers. CD4-positive cell counts in peripheral blood were 5.8/μL (Case 1) and 79.9/μL (Case 2) in the HIV carriers and 3285/μL in the HTLV-1 carrier (Case 3). According to flow cytometric analysis of the lymph nodes of Cases 1, 2, and 3, 50.0%, 87.1%, and 85.9%, respectively, of the T-cells were CD3; 9.8%, 16.3%, and 75.8%, respectively, were CD4; and 35.5%, 77.3%, and 10.2%, respectively, were CD8. Cryptococcus neoformans was detected in tissue culture in all patients. Although gelatinous lesions and numerous fungal cocci were observed in the two HIV patients, the granuloma formation was small. Gelatinous formation and granuloma formation were observed in the HTLV-1 carrier. Necrosis was observed in all cases. In previous reports, granuloma formation, epithelioid cells, and necrotic lesions were observed in most cases. Most of the patients were also immunosuppressed. However, no HTLV-1 carrier was detected. In conclusion, lymphadenopathy in a HTLV-1 carrier may suggest the presence of cryptococcal lymphadenitis. The frequency of cryptococcosis in HTVL-1 carriers may increase with increase in the long-term survival rate of HTLV-1 carriers.

Macrophages are closely related to various diseases and it is therefore important that the properties of macrophages are adequately evaluated in human diseases and mouse disease models. Immunohistochemistry (IHC) of formalin fixed paraffin-embedded (FFPE) samples is a very useful tool for examination of macrophages; however, an adequate IHC protocol is required for the examination of macrophage states. In this study, we assessed various antigen retrieval methods in order to devise the optimal protocols for staining of macrophages with a range of antibodies. Optimum combinations of primary antibodies and antigen retrieval protocols were determined; for example, heat treatment with ethylenediamine tetraacetic acid solution, pH 8.0, was the best procedure for IHC using mouse anti-Iba1 and human anti-CD11b, -CD163, -CD169, -CD204, and -CD206 antibodies. Moreover, we found that the immunoreactivity of sliced tissue sections decreased gradually over time in long term storage but that this immunoreactivity was preserved in storage at -80 °C in a deep freezer. The optimal IHC protocols and storage procedures that were determined in this study should be a useful tool for macrophage research.