MOG autoantibodies trigger a tightly-controlled FcR and BTK-driven microglia proliferative response

Autoantibodies are a hallmark of numerous neurologic disorders, including multiple sclerosis (MS), autoimmune encephalitides and neuromyelitis optica (NMO). While well understood in peripheral myeloid cells, the pathophysiological significance of autoantibody-induced Fc receptor (FcR) signaling in microglia remains unknown, in part due to the lack of a robust in vivo model. Moreover, application of therapeutic antibodies for neurodegenerative disease also highlights the importance of understanding FcR signaling in microglia. Here, we describe a novel in vivo experimental paradigm that allows for selective engagement of Fc receptors within the CNS by peripherally injecting anti-myelin oligodendrocyte glycoprotein (MOG) monoclonal antibodies (mAbs) in normal wild-type mice. MOG antigen-bound immunoglobulins were detected throughout the CNS and triggered a rapid and tightly regulated proliferative response in both brain and spinal cord microglia. This microglial response was abrogated when anti-MOG antibodies were deprived of Fc effector function or injected into Fc γ R knockout mice and was associated with the downregulation of FcRs in microglia, but not peripheral myeloid cells, establishing that this response was dependent on central FcR engagement. Downstream of FcRs, Bruton's tyrosine kinase (BTK) was a required signaling node for this response, as microglia proliferation was amplified in BTKE41K knock-in mice expressing a constitutively active form of BTK and blunted in mice treated with a CNS penetrant small molecule inhibitor of BTK. Finally, this response was associated with transient and stringently regulated changes in gene expression predominantly related to cellular proliferation, which markedly differed from transcriptional programs typically associated with FcR engagement in peripheral myeloid cells. Together, these results establish a physiologically-meaningful functional response to FcR and BTK signaling in microglia while providing a novel in vivo tool to further dissect the roles of microglia-specific FcR and BTK-driven responses to both pathogenic and therapeutic antibodies in CNS homeostasis and disease.

Tumour-reactive lymphocytes stimulated in mixed lymphocyte and tumour culture. Clonal analysis of effector cells in cytotoxic and proliferative assays

Lymphocytes from cancer patients were stimulated in mixed culture with autologous tumour (MLTC) or pooled allogeneic lymphocytes (MLC). Both protocols induced increased uptake of 3H-thymidine at 5 days and the appearance of lymphoblasts. Blasts were isolated on discontinuous Percoll gradients and either expanded as bulk cultures or cloned directly under limiting dilution conditions in the presence of conditioned medium containing IL-2. Results with MLTC-blast-CTC have been reported elsewhere. MLC-activated cultures lysed autologous tumour but not autologous lymphoblasts. Lysis of some allogeneic tumours, lymphoblasts from members of the inducing pool, and K562 was also apparent. MLC activated cultures did not undergo restimulation in response to autologous tumour or lymphocytes but were restimulated by leukocytes from pool members. MLTC clones showed autologous tumour-specific cytotoxic activity or cross-reactive proliferative responses with tumours of the same site and histology. The majority of MLC clones cytotoxic for autologous tumour were also specific and did not lyse allogeneic tumour, K562, or lymphoblasts from the inducing pool. Two clones lysed autologous tumour and pool members. None of the clones tested proliferated in response to autologous tumour following MLC activation but some were responsive to pool members and one clone was restimulated by autologous monocytes. No association was found between clone phenotype and function. The implication of these data is that the effector cells with activity against autologous tumour induced in MLC arose largely by transstimulation of in vivo-activated tumour reactive lymphocytes by IL-2 release rather than expansion of NK-like effectors or sharing of antigenic specificities between tumour and allogeneic lymphocytes. Since MLC activation of cancer patients lymphocytes does not induce proliferative responses to autologous tumour it is unlikely to be a useful procedure in preparing cells for immunotherapy protocols.

Importance of MHC antigen expression on solid tumors in the in vitro interaction with autologous blood lymphocytes

In 54 patients with lung and 14 with ovarian carcinomas the quantitative variations of the major histocompatibility complex (MHC)-determined class I and class II antigens of the tumor cells were related to their in vitro interaction with blood lymphocytes, to the lymphoid infiltration of the tumors, and to the metastatic state of the disease. The tumor cell-lymphocyte interaction was measured by the proliferative response in mixed lymphocyte tumor cell culture and by the cytotoxic activity of the lymphocytes. The results showed that (1) none of the 23 tumors from patients with disseminated disease were lysed; (2) class I-negative tumors were not damaged; (3) lymphoid infiltration was present in a higher proportion of class II-positive tumors; and (4) both MHC-positive and -negative tumors were found among the disseminated tumors. The requirement of class I expression in the lytic interaction substantiates our earlier conclusion concerning the cytotoxic T lymphocyte nature of lymphocyte-mediated auto-tumor lysis. The lack of auto-tumor lysis in patients with metastases suggests impairment of lymphocyte function in advanced stages of the disease.

Cell-mediated immunity to chemically xenogenized tumors. I. Inhibition by specific antisera and H-2 association of the novel antigens

T cell-mediated proliferative and cytotoxic responses occur in vitro to syngeneic tumor cells antigenically altered by mutagen treatment. One such xenogenized variant of the murine L5178Y lymphoma elicits IgG antibodies reactive with determinants on variant cells that are not expressed at detectable levels on parental or normal cells of the same H-2d haplotype and are also unrelated to public specificities of H-2b or H-2k histocompatibility antigens. In the present study we investigated the effect of those antibodies on development of cell-mediated responses in vitro to the xenogenized cells used for induction of the humoral response. The proliferative reaction, generation of cytolytic activity and target cell lysis were all inhibited by the anti-xenogenized tumor immune serum, whereas the corresponding reactions to the parental cells by syngeneic or allogeneic effector lymphocytes were not. In order to investigate the possible H-2 association of T cell-mediated responses to xenogenized cells, we also examined the effect on those reactions of antibodies specific for Class I or Class II products of the H-2d complex. The results obtained suggested a role for I-Ad molecules in the T cell proliferative response to the xenogenized cells, and also indicated a preferential association of the cytotoxic response with H-2Kd determinants.

Effect of oral administration of kynurenic acid on the activity of the peripheral blood leukocytes in mice

Kynurenic acid (KYNA), an endogenous tryptophan metabolite, is a selective ligand of the GPR35 receptor, expressed mainly on the immune cells. In inflammatory conditions, by affecting this receptor, KYNA inhibits the synthesis of pro-inflammatory cytokines and probably protects tissues from oxidative damage. However, we lack data regarding the effect of exogenous KYNA on the activity of immune cells in healthy individuals. The objective of this study has been to determine the influence of kynurenic acid administered to mice in different doses (2.5, 25 or 250 mg/l) and for different time periods (3, 7, 14, 28 days) in drinking water, on the activity of their peripheral blood leukocytes. The determinations comprised the proliferative activity of lymphocytes (MTT assay) and the phagocytic activity as well as the respiratory burst activity of granulocytes and monocytes (Phagotest, Phagoburst). It was only the lowest KYNA dose that influenced the mitogenic response of lymphocytes, namely by increasing the proliferation of T cells. The impact on the phagocytic activity was varied with KYNA dose and administration time. However, all the KYNA doses significantly lowered the activity of oxidative burst in phagocytes, which was probably associated with its antioxidant properties. In the light of the research results, kynurenic acid may find applications as an immuno-modulating agent able to correct an excessive or insufficient response of phagocytizing cells, protecting an organism from oxidative stress.

Potentiation of interleukin-2 production and its binding by monoclonal antibodies to the gangliosides GD3 and GD2

Previous studies have shown that monoclonal antibodies (mAbs) against certain gangliosides, which induced remissions in patients with melanoma, also potentiated the response of lymphocytes to a variety of stimuli, including lectins, interleukin-2 (IL-2) and antigens. The present studies have investigated the mechanism of these effects on lymphocytes. Although the mAbs potentiated phytohemagglutinin(PHA)-induced IL-2 production at high concentrations of mAbs and of PHA, this did not appear to explain their potentiation of the proliferative responses of lymphocytes. Hence, although IL-2 production was minimal or absent from the CD8+ subset the latter showed the highest degree of augmentation. Furthermore, addition of IL-2 to PHA-stimulated cultures did not produce similar augmentation of mitogenic responses to that produced by the mAb to GD3 or GD2. The augmented and normal mitogenic responses were, however, dependent on IL-2, as shown by their inhibition with mAbs against IL-2. The antiganglioside mAbs did not have significant effects on IL-2 receptor expression measured by mAbs to Tac. However, the mAbs appeared to increase the affinity of binding of radiolabelled IL-2 to IL-2 receptor and increased internalization of the latter. These results suggest that the effects of the mAbs on IL-2 production may be distinguished from their effects on the proliferative responses of T cells and that the latter were associated with changes in affinity and internalization of 125I-IL-2. Whether the latter is a direct cause of the increased proliferative response remains unknown. The ability of mAbs to GD2 and GD3 to increase IL-2 production and to "enhance" IL-2-dependent proliferative responses suggests the may have valuable clinical roles as immunopotentiating agents.

Immune functions and the prognosis of patients with solid tumours

The immune competence of 169 patients with solid malignant tumours was assessed before initiation of radiotherapy or chemotherapy and followed during the course of the disease. The data of years 1974-1984 were collected and subjected to an analysis in order to evaluate their prognostic significance. The number of leucocytes and lymphocytes in the peripheral blood, the percentage or absolute number of E-rosette forming cells or EAC-rosette forming cells or serum immunoglobulin levels did not show any association with the prognosis. Lymphocyte proliferative responses to PHA, Con A and PPD as studied before initiation of the treatment did not correlate with recurrence or final prognosis of the disease, except that the responses to PPD were slightly lower in patients with recurrence of gynaecological cancer, melanoma or gastrointestinal cancer than in their respective control patients. In the values observed after the first treatment course a low response to PPD was associated with poor prognosis in patients with melanoma or gastrointestinal cancer. At the time of recurrent disease the PPD response showed an association with a poor final outcome in patients with gastrointestinal malignancy. Of the responses assessed less than 3 months before death due to cancer, only in patients with breast cancer were low Con A responses seen; in all patient groups the PHA responses decreased in the terminal patients. The results do not support the idea that the methods currently available should be routinely used in the follow-up of cancer patients; rather, they indicate the need to seek new methods for this purpose.

DR antigen expression on ovarian carcinoma cells does not correlate with their capacity to elicit an autologous proliferative response

Expression of HLA-DR antigens by purified preparations of human ovarian carcinoma cells freshly isolated from surgical specimens was examined in parallel with the capacity of tumor cells to elicit a blastogenic response from autologous lymphocytes in mixed lymphocyte-tumor culture (MLTC) assay. Of 21 tumor preparations, 11 (52%) reacted with monoclonal antibodies 279 and/or 949 specific for a monomorphic determinant of HLA-DR antigens, with heterogeneous positivity, ranging between 30% and 95%. In this series of patients positive MLTC occurred in 8/21 individual experiments. The HLA-DR expression was proportionally similar in tumors giving positive MLTC (4/8 = 50%) and negative MLTC (7/13 = 53%). The lack of correlation between DR expression on tumor cells and stimulatory activity in autologous MLTC and the fact that DR-negative tumors could induce lymphocyte stimulation, support the hypothesis that blastogenesis occurs upon recognition of tumor-associated antigens, different from DR molecules, possibly tumor-specific antigens.

Stimulated proliferative responses in vertically HIV-infected children on HAART correlate with clinical and immunological markers

The objective of the study was to investigate the relationship between various CD4+ T cell subsets and the ability of peripheral blood mononuclear cells (PBMC) to proliferate to several stimuli in vertically human immunodeficiency virus type 1 (HIV-1)-infected children. We studied 29 HIV-1-infected children on highly active antiretroviral therapy (HAART) (median duration: 12.3 months). T cell subsets were determined by flow cytometry. Plasma viral load (VL) was quantified using a standardized molecular method. Proliferative responses were evaluated by [3H]-thymidine incorporation. Decreased proliferative responses of PBMC to pokeweed mitogen (PWM) were found for HIV-1-infected children in Centers for Disease Control (CDC) clinical categories B and C when compared to the control group (P < 0.05). Similarly, children with < or = 15% CD4+ T cells showed a decrease in proliferative responses to PWM (P < 0.01), anti-CD3 + anti-CD28 (P < 0.01) and phytohaemagglutinin (PHA) (P < 0.05) with respect to the control group and to children with CD4+ T cells > or = 25%. Proliferative responses to PWM, anti-CD3+, anti-CD28 and PHA had a statistically significant positive correlation with CD3+/mm3, CD4+/mm3, % CD4 T cells, CD4/CD8 ratio and the percentage of naive T cell subsets (CD4+CD45RO-HLA-DR-, CD4+ CD45RA+ CD62L+, CD4+ CD45RA+), CD4+ CD62L+ and CD4+ T cells co-expressing CD38+ (CD4+ HLA-DR-CD38+, CD4+ CD38+). Moreover, we found a negative correlation between PBMC proliferative responses and % CD8 T cells, memory, memory-activated and activated CD4+ T cell subsets. Lower proliferative responses to PWM (P < 0.01) and PHA (P < 0.01) were associated with higher VL. Our data show that higher proliferative responses to PWM, anti-CD3 + anti-CD28 and PHA are associated with both non-activated and naive CD4+ T cell subsets in HIV-1-infected children on HAART.

Antitumor activity in vitro in chronic myelogenous leukaemia revealed after treating peripheral cells with cytosine arabinoside

Cytosine arabinoside (Ara-C) treatment of peripheral blood mononuclear cells from 12/12 chronic-phase chronic myelogenous leukaemia (CML) patients revealed a proliferative response stimulated by their untreated leukaemic cells. Specific recognition of tumour cells by patients' normal lymphocytes was suggested by the finding that cells of siblings genotypically identical for human leukocyte antigen caused no stimulation. Lymphocytes thus stimulated by tumour cells from one of these patients were cloned by limiting dilution and tested for antileukaemic effects in cytotoxicity and proliferation assays. Cytotoxic lines were isolated that killed autologous CML targets but only a limited number of allogeneic fresh leukaemias or cell lines. These results show that anti-leukaemia effectors can be isolated from chronic-phase CML patients and suggest their potential application in adoptive immunotherapy.

Proliferation capability of natural killer cells upon cytokines stimulation correlated negatively with serum lactate dehydrogenase level in coronary artery disease patients

Background

Natural killer (NK) cells are proposed to participate in coronary artery disease (CAD) development. However, little is known about how CAD patients' NK cells respond to different stimulatory factors in terms of proliferation capability.

Methods and results

Twenty-nine CAD patients' peripheral blood NK cells were isolated and individually treated with IL-2, IL-12, IL-15, IL-18, IL-21, cortisone acetate, hydrocortisone, or ascorbic acid for 36 hours, followed by cell cycle analysis using flow cytometry. The ratio of S and G2/M phase cell number to total cell number was defined as a proliferation index (PrI) and used for proliferative capability indication. The results showed that these eight factors resulted in different life cycle changes in the 29 NK cell samples. Remarkably, 28 out of 29 NK cell samples showed an obvious increase in PrI upon ascorbic acid treatment. The serum lactate dehydrogenase (LDH) level of the 29 CAD patients was measured. The results showed a negative correlation between serum LDH level and the CAD patients' NK cell PrI upon stimulation of interleukins, but not the non-interleukin stimulators. Consistently, a retrospective analysis of 46 CAD patients and 32 healthy donors showed that the circulating NK cell number negatively correlated with the serum LDH level in CAD patients. Unexpectedly, addition of LDH to NK cells significantly enhanced the production of IFN-γ, IL-10 and TNF-α, suggesting a strong regulatory role on NK cell's function.

Conclusion

Ascorbic acid could promote the proliferation of the CAD patients' NK cells; LDH serum level may function as an indicator for NK cell proliferation capability and an immune-regulatory factor.

[Medicamental correction of pathomorphological changes of the ocular surface in patients with steroid therapy intolerance after photorefractive keratectomy]

INTRODUCTION

The problems of controlling inflammatory and proliferative response of the retina and correcting tear production in the post-operative period after photorefractive keratectomy (PRK) have not been fully solved yet. Patients intolerable to local steroids require an alternative. One drug that covers those needs is Cyclosporine 0.05%.

PURPOSE

To analyze clinical effectiveness of Restasis eye drops in solving inflammatory-degenerative response and tear production insufficiency (dry eye syndrome) for post-PRK patients with steroid eye drops intolerance accompanied with increasing intraocular pressure (IOP).

PATIENTS AND METHODS

Retrospective analysis of 14 myopic patients (28 eyes) was conducted; mean patient age was 25.9±6 years; myopia was (-)5.65±1.5 Diopters of spherical equivalent (SE); corneal-compensated IOP was 16.98±3.68 mm Hg before the surgery. All patients underwent excimer laser correction (PRK or Trans-PRK) with Schwind Amaris (SCHWIND eye-tech-solutions). After epithelization, all patients were prescribed 0.1% Dexamethasone solution 4 times a day (with decreasing dosing frequency) for 2 months, as well as local lubricants. The article also describes a separate clinical case of subepithelial fibroplasia that occurred post-PRK and was successfully stopped.

RESULTS

All patients had transitory IOP increase caused by local steroid therapy. Mean IOP at 1-month post-op was 20.5±7 mm Hg. At that point local steroids were replaced with 'Restasis' 0.05% (Cyclosporine) eye drops prescribed 2 times per day for 2 months. As the result, IOP values decreased to 16.2±3.21 mm Hg (without any additional therapy); at 6 months mean uncorrected visual acuity reached 0.98±0.05, best corrected visual acuity achieved 1.03±0.06 and SE was 0.04±0.12 Diopters.

CONCLUSION

Local Cyclosporine ('Restasis') is the method of choice for regulation of inflammatory and degenerative response and tear production insufficiency (dry eye syndrome) for post-PRK patients with intolerance to steroid eye drops.