Proliferative patterns of lymphocytes in lymph nodes during tumour development: involvement of T and B cell areas

Regulatory B cells producing IL-10 are increased in human tumor draining lymph nodes

The contribution of different immune cell subsets, especially T cells, in anti-tumor immune response is well established. In contrast to T cells, the anti-tumor contribution of B cells has been scarcely investigated. B-cells are often overlooked, even though they are important players in a fully integrated immune response and constitute a substantial fraction of tumor draining lymph nodes (TDLNs) known also as Sentinel Nodes. In this project, samples including TDLNs, non-TDLNs (nTDLNs) and metastatic lymph nodes from 21 patients with oral squamous cell carcinoma were analyzed by flow cytometry. TDLNs were characterized by a significantly higher proportion of B cells compared with nTDLNs (P = .0127). TDLNs-associated B cells contained high percentages of naïve B cells, in contrary to nTDLNs which contained significantly higher percentages of memory B cells. Patients having metastases in TDLNs showed a significantly higher presence of immunosuppressive B regulatory cells compared with metastasis-free patients (P = .0008). Elevated levels of regulatory B cells in TDLNs were associated with the advancement of the disease. B cells in TDLNs were characterized by significantly higher expression of an immunosuppressive cytokine-IL-10 compared with nTDLNs (P = .0077). Our data indicate that B cells in human TDLNs differ from B cells in nTDLNs and exhibit more naïve and immunosuppressive phenotypes. We identified a high accumulation of regulatory B cells within TDLNs which may be a potential obstacle in achieving response to novel cancer immunotherapies (ICIs) in head and neck cancer.

Therapeutic efficacy of multipotent adult progenitor cells versus mesenchymal stem cells in experimental autoimmune encephalomyelitis

AIM

In this study, we have evaluated the therapeutic efficacy of mouse multipotent adult progenitor cells (mMAPCs) in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, and compared it with mouse mesenchymal stem cells (mMSCs).

MATERIALS & METHODS

We administered PKH26-labeled mMAPC and mMSC into EAE mice and evaluated their therapeutic efficacy.

RESULTS

The mMAPC-treated mice in comparison with the mMSC group exhibited a higher suppression of EAE (p < 0.05), and a higher fold expression of neuronal genes GAP43, NG2, PDGFR, Nestin, SMI 32, BDNF and NT 3 in spinal cord (p < 0.05), suggesting a better neuroprotective and regenerative potential of mMAPC than mMSC.

CONCLUSION

MAPC may be a potential cell type, which is superior to mesenchymal stem cell for the treatment of EAE/multiple sclerosis.

Distinct mechanisms of B and T lymphocyte accumulation generate tumor-draining lymph node hypertrophy

Tumor-draining lymph nodes (TDLNs) often enlarge in human cancer patients and in murine tumor models, due to lymphocyte accumulation and lymphatic sinus growth. B lymphocytes within TDLNs can drive lymph node hypertrophy in response to tumor growth, however little is known about the mechanisms directing the preferential accumulation of B lymphocytes relative to T cells in enlarging TDLNs. To define why B and T lymphocytes accumulate in TDLNs, we quantified lymphocyte proliferation, apoptosis, entry, and exit in TDLNs versus contralateral non-TDLNs (NTDLNs) in a footpad B16-F10 melanoma mouse model. B and T lymphocyte proliferation and apoptosis were increased as the TDLNs enlarged, although relative rates were similar to those of NTDLNs. TDLN entry of B and T lymphocytes via high endothelial venules was also modestly increased in enlarged TDLNs. Strikingly, the egress of B cells was strongly reduced in TDLNs versus NTDLNs, while T cell egress was modestly decreased, indicating that regulation of lymphocyte exit from TDLNs is a major mechanism of preferential B lymphocyte accumulation. Surface sphingosine-1-phosphate receptor 1 (S1PR1) which binds S1P and signals lymphocyte egress, exhibited greater downregulation in B relative to T lymphocytes, consistent with preferential retention of B lymphocytes in TDLNs. TDLN lymphocytes did not activate surface CD69 expression, indicating a CD69-independent mechanism of downregulation of S1PR1. B and T cell trafficking via afferent lymphatics to enter TDLNs also increased, suggesting a pathway for accumulation of tumor-educated lymphocytes in TDLNs. These mechanisms regulating TDLN hypertrophy could provide new targets to manipulate lymphocyte responses to cancer.

Local immune reaction in syngeneic mice against tumorigenic and nontumorigenic BPV-transformed mouse cell lines

The role of cytotoxic T cells in immune response to Bovine Papillomavirus type 1 (BPV1)-transformed mouse cell lines was assessed. The chromium release assay was used to follow the induction of cytotoxicity in local lymph nodes of syngeneic C57BL/6J (B6) mice after injection of BPV1-transformed cell lines tumorigenic in nude mice but tumorigenic or nontumorigenic in B6 mice. The nontumorigenic cell line B6B31.C-NuT.A induced cell line-specific cytotoxicity with a maximal activity on day 7 after subcutaneous inoculation of one million B6B31.C-NuT.A cells. After injection of nontumorigenic B6B31.J or tumorigenic B6B31.J-NuT.A or B6B31.A cell lines, only low levels of nonspecific cytotoxicity were observed. These results suggest a role for cytotoxic T cells only in rejection of B6B31.C-NuT.A cells. One reason for the poor immunogenicity could be the lack of transformation-induced/virus-specific antigens on most of the present BPV1-transformed cell lines. However, in a transplantation rejection experiment, protection was induced in B6 mice against a challenge of the highly tumorigenic B6B31.A-B6T.1 line by repeated injections of BPV1-transformed cells. These results suggest the expression of common transplantation rejection antigens on the three BPV1-transformed cell lines used in the immunization experiments.

Immune response against P815X2 mastocytoma growing in syngeneic DBA/2 mice. I. Morphometric assessment of lymph node immunoreactivity and analysis of circulating antibodies

To assess the significance of humoral immune mechanisms in host reactivity against the P815X2 mastocytoma grown in syngeneic DBA/2 mice, an approach was made to correlate immunomorphology of the lymph nodes with the functional assays measuring cytotoxic and tumor cell membrane-bound antibodies in mouse sera. Regional and non-regional (RLN, NRLN) lymph nodes, were subjected to stereological analysis to determine the volume fractions (Vv) of the cortex (C), the paracortex (PCA), the germinal centers (GC), and the medulla (M), using a computerized analysis system (IBAS I, Kontron). In both RLN:s and NRLN:s, lymphocyte subsets were identified and their ratios determined using the ABC (avidin-biotin peroxidase complex) technique and following monoclonal antibodies; Anti-Thy 1.2, Anti-Lyt 1, Anti-Lyt 2, and Anti-I-Ad. The 51Cr release assay was used to test the mouse sera for cytotoxic antibodies, and an indirect immunofluorescence (IF) technique to assess the sera for tumor cell membrane-bound antibodies. There was a marked enlargement of the RLN:s reaching the peak on day 12, due to increase of the Vv of the B-zone as well as of the T-zone. Evidence of distinct B-cell stimulation by the growing of P815X2 was provided by an early decrease of Thy1.2+/I-Ad+ cell ratio both in the RLN:s and in NRLN:s. This activation of B-cells seems to be parallel to the elevation of Lyt1+/Lyt2+ ratio in T-cell region on day 6. The IF-tests for or the presence of tumor cell membrane-bound antibodies were almost invariably negative. With exception of two sera, the 51Cr-release assay for cytotoxic antibodies against P815X2 targets was negative. The present study confirms the previous observations on failure to find circulating cytotoxic or cell membrane-bound antibodies in DBA/2 mice bearing P815X2 mastocytoma, despite the morphologically well definable activation in RLN:s and in NRLN:s of the B-cell areas. This is in alignment with the findings in the majority of human tumors, where B-cell predominance in RLN:s does not represent a favourable prognostic sign.

Immune response against P815X2 mastocytoma growing in syngeneic DBA/2 mice. II. Morphometric assessment of immunoreactivity in the thymus and spleen related to lymphocyte subsets in peripheral blood

To assess the significance of humoral immune mechanisms in host reactivity against the P815X2 mastocytoma grown in syngeneic DBA/2 mice, an approach was made to correlate immunomorphology of the thymus and spleen with the functional assays measuring cytotoxic (51Cr-release assay) and tumor cell membrane-bound antibodies (IF test) as well as phenotyping (with monoclonal antibodies Anti-Thy1.2, Anti-Lyt1, Anti-Lyt2, and Anti-I-Ad) the lymphocyte subsets in peripheral blood. The volume fractions (Vv) of the cortex (C), and medulla (M) of the thymus, as well as central (C-PALS) and peripheral periarteriolar lymphoid sheath (P-PALS) in the spleen were determined morphometrically. There was a steady increase of the C/M ratio from the control levels until day 8, not accompanied by any major fluctuations in the percentages of Thy1.2+ or I-Ad+ cells in C and M. In M, two significant peaks were found in Lyt1+/Lyt2+ cell ratio. In the spleen P-PALS, Thy1.2+/I-Ad+ cell ratio was subject to major early elevation, followed by a rapid and permanent decline to levels below the controls. Two high peaks of Lyt1+/Lyt2+ ratio were found in P-PALS, on day 10 and 16. In the C-PALS, a marked decline in Thy1.2+/I-Ad+ ratio was observed throughout the experiment. As determined by Vv, there was a marked early enlargement of P-PALS reaching the peak on day 4, and followed by a steady reduction reaching the control values on day 10. In peripheral blood, there was an initial increase of T-cells, leading to elevated Thy1.2+/I-Ad+ ratio and a subsequent elevation of Lyt1+/Lyt2+ ratio on day 8.(ABSTRACT TRUNCATED AT 250 WORDS)