THU0439 EFFICACY AND SAFETY OF ANAKINRA IN THE TREATMENT OF RECURRENT GOUT FLARES: RESULTS FROM THE EXTENSION PHASE OF THE ANAGO STUDY

Background:

The anaGO (anakinra ingout) study was a multi-center, randomized, double-blind, double-dummy, phase 2 study investigating the efficacy and safety of anakinra for recurrent gout flares. Results from subsequent flares (extension phase) are presented in relation to the previously reported results from the 1stflare (flare at study enrollment).

Objectives:

The objective of the extension phase was to evaluate the efficacy, safety and immunogenicity of two anakinra regimens (100 or 200 mg daily s.c. injections for 5 days) compared to triamcinolone (single i.m. injection 40 mg) for subsequent flares after initial study enrollment flare. The primary endpoint of the study was change in patient-assessed flare pain intensity from baseline to 24-72 hours (average of 24, 48 and 72 hours) in the most affected joint measured on a visual analogue scale (0-100 VAS). Secondary endpoints included: patient’s and physician’s assessments of global response, anti-drug antibodies (ADA) and safety.

Methods:

The study included patients with acute gout (ACR/EULAR 2015 gout classification criteria) unsuitable for anti-inflammatory therapy with NSAIDs and colchicine due to contraindication, intolerance or inefficacy. Patients were eligible for treatment of subsequent flares for up to 2 years. Each patient received the same treatment for all flares, starying with the flare at enrollment.

Results:

161 patients were treated for 1 flare, 61 patients for 2 flares, 31 patients for 3, and 20 patients for 4 or more flares with 1 patient treated for 9 flares. In total, 300 flares were treated in the full study; anakinra 100 mg and 200 mg, 107 and 106 flares, respectively; and triamcinolone, 87 flares. Both anakinra doses and triamcinolone provided a clinical meaningful reduction in patient-assessed pain intensity in both the 1stand subsequent flares. Mean changes in pain intensity from baseline to 24–72 hours for total anakinra and triamcinolone were: 1stflare -41.2 and -39.4; 2ndflare -33.9 and -31.1; 3rdflare -31.8 and -51.2, respectively. Mean differences in pain reduction between anakinra and triamcinolone treatment groups were (negative value favors anakinra): 1stflare -1.8, 2ndflare -2.8 3rdflare 19.4. The majority of secondary endpoints favored anakinra, including patient’s and physician’s global assessement of response and physician’s assessement of the joint. No unexpected safety findings during subsequent flares were identified. 21 patients (19.6%) developed ADA to anakinra in low titers at some time point; 7 (6.5%) had pre-existing ADA at baseline and 12 (11.2%) developed treatment induced ADA. 2 patients had pre-existing ADA to triamcinolone at baseline. 4 patients on anakinra (3.7%) developed neutralizing antibodies (NAbs). Pre-dose 72 hour anakinra serum concentrations were in similar range for ADA+ and ADA- patients. Presence of ADA was not associated with adverse events or had an impact on pain reduction.

Conclusion:

The efficacy and safety of anakinra and triamcinolone in subsequent flares were similar to the findings from 1stflare in patients with acute gout. Patient-assessed pain in the 1stand 2ndflare was reduced to similar degrees in all treatment groups, but to a larger extent in the 3rdflare in the small triamcinolone group. Secondary endpoints were in favor of anakinra across flares 1 to 3. The overall incidence of ADA and NAb was low also after repeated anakinra dosing and did not appear to impact exposure, efficacy or safety. In conclusion, anakinra was shown to be an option in the treatment of recurrent gout flares in patients for whom conventional therapy is unsuitable.

Disclosure of Interests: :

Kenneth Saag Grant/research support from: Horizon, Sobi, Shanton, Grant/research support from: Horizon Pharma, Sobi, Shanton, Consultant of: Horizon and Sobi, Consultant of: Horizon Pharma, Amgen, Radius, LG-Pharma, Takeda, Sobi, Atom, Arthrosi, Puja Khanna Grant/research support from: Dyve, Selecta, Sobi, Consultant of: Sobi, Horizon, Robert Keenan Consultant of: Sobi, Selecta, Horizon, Sven Ohlman Shareholder of: Sobi, Employee of: Former employee of Sobi, Erik Sparve Shareholder of: Sobi, Employee of: Sobi, Daniel Lindqvist Employee of: Sobi, Ann-Charlotte Åkerblad Shareholder of: Sobi, Employee of: Sobi, Margareta Wikén Shareholder of: Sobi, Employee of: Former employee of Sobi, Alexander So Consultant of: Sobi, Grünenthal, Michael H. Pillinger Grant/research support from: Horizon, Hikma, Consultant of: Sobi, Horizon, Robert Terkeltaub Consultant of: Sobi, Selecta, Horizon, Astra-Zeneca

AB1059 A RANDOMIZED, PLACEBO-CONTROLLED STUDY OF ANAKINRA IN PATIENTS WITH STILL´S DISEASE

Background:

Adult-onset Still’s disease (AOSD) and systemic juvenile idiopathic arthritis (SJIA) are rare autoinflammatory disorders associated with an activated IL-1 pathway, characterized by spiking fever, rash, arthritis, lymphadenopathy, hepatosplenomegaly and serositis. There is a growing understanding that SJIA and AOSD are one disease with different ages of onset, i.e. Still’s disease. The anaSTILLs study (anakinra inStill´sdisease) was designed to further evaluate efficacy and safety of anakinra in patients with Still´s disease across all age groups.

Objectives:

The primary objective was to demonstrate efficacy of anakinra versus placebo as assessed by ACR30 response with absence of fever at Week 2. Secondary objectives included: early onset of efficacy, sustained efficacy, time to study drug discontinuation, safety, pharmacokinetics, clinical signs and biomarkers.

Methods:

‘anaSTILLs’ was a randomized, double-blind, placebo-controlled, 12-week study including patients with active and newly diagnosed (6 months) Still´s disease according to adapted ILAR criteria if <16, or Yamaguchi criteria, if ≥16 years of age at disease onset. Patients were randomized to anakinra 2 mg/kg (max 100 mg/day), 4 mg/kg (max 200 mg/day) or placebo.

Results:

12 patients were randomized and received study drug: 6 anakinra (2 mg/kg n=2, 4 mg/kg n=4) and 6 placebo, the study was terminated early due to slow recruitment. 1 patient on placebo had lymphoma, not Still’s disease, and was excluded; thus in total 11 patients were analyzed for efficacy, 8 were children [median (range) age=4.0 (1-11) years] and 3 were adults [median (range) age=32.0 (25-51) years]. 55% were male and the mean symptom duration was 74.2 days. All patients on anakinra but none on placebo achieved ACR30 response with absence of fever at Week 2 (p-value=0.0022). The efficacy of anakinra was further demonstrated by superiority to placebo in ACR50/70/90 responses with absence of fever at Week 2. All placebo patients discontinued the study within 6 weeks, 2 due to progressive disease, 2 due to lack of efficacy and 1 due to withdrawal by patient. There was a numerically higher proportion with early onset of efficacy (Week 1) in the anakinra group compared to placebo. The ACR30/50/70/90 responses in the anakinra group were sustained throughout the study period. Patients in the anakinra group had a prompt and persistent decrease in CRP and ferritin levels at Week 1, which was not observed in the placebo group. There were no unexpected safety findings. All anakinra patients developed anti-drug antibodies (ADAs) at some timepoint during the study. ADAs were persistent throughout the treatment period, except in one patient. Titers were low to moderate. One placebo patient had low ADA titers at one occasion. No neutralizing antibodies were observed and the ADAs did not appear to impact clinical efficacy or safety.

Conclusion:

Anakinra is superior to placebo in the treatment of Still’s disease. ADAs occur frequently but do not appear to adversely impact efficacy or safety. These results confirm the benefits of anakinra treatment in patients with active, newly diagnosed Still´s disease across ages.

Disclosure of Interests:

Laura Schanberg Grant/research support from: Sobi, BMS, Consultant of: Aurinia, UCB, Sanofi, Peter Nigrovic Grant/research support from: Novartis, BMS, Pfizer, Consultant of: Novartis, BMS, Pfizer, Sobi, Miach Orthopedics, Simcere, XBiotech, Quench Bio, Ashley Cooper: None declared, Winn Chatham Grant/research support from: Sobi, Consultant of: Sobi, Shoghik Akoghlanian: None declared, Namrata Singh: None declared, Egla Rabinovich Grant/research support from: AbbVie, UCB Pharma, Janssen Research & Development, Akaluck Thatayatikom: None declared, Alysha Taxter: None declared, Jonathan Hausmann Consultant of: Novartis, Milan Zdravkovic Shareholder of: Sobi, Employee of: Sobi, Sven Ohlman Shareholder of: Sobi, Employee of: Former employee of Sobi, Henrik Andersson Employee of: Sobi, Susanna Cederholm Shareholder of: Sobi, Employee of: Sobi, Margareta Wikén Shareholder of: Sobi, Employee of: Former employee of Sobi, Rayfel Schneider Grant/research support from: Roche, Novartis, Sobi, Pfizer, Consultant of: Sobi, Novartis, Novimmune, Fabrizio De Benedetti Grant/research support from: AbbVie, Pfizer, Novartis, Novimmune, Sobi, Sanofi, Roche, Speakers bureau: AbbVie, Novartis, Roche, Sobi

Dynamic Changes in Resident and Infiltrating Epidermal Dendritic Cells in Active and Resolved Psoriasis

Epidermal Langerhans cells (LCs) are spatially separated from dermal dendritic cells (DCs) in healthy human skin. In active psoriasis, maintained by local production of IL-23 and IL-17, inflammatory DCs infiltrate both skin compartments. Here we show that CCR2⁺ epidermal DCs (eDCs) were confined to lesional psoriasis and phenotypically distinct from dermal DCs. The eDCs exceeded the number of LCs and displayed high expression of genes involved in neutrophil recruitment and the activation of keratinocytes and T cells. Resident LCs responded to toll-like receptor 4 and toll-like receptor 7/8 activation with increased IL-23 production, whereas eDCs additionally produced IL-1β together with IL-23 and tumor necrosis factor. Psoriasis typically recur in fixed skin lesions. eDCs were absent from resolved psoriasis. Instead, LCs from anti-tumor necrosis factor-treated lesions retained high IL23A expression and responded to toll-like receptor stimulation by producing IL-23. Our results reveal phenotypic and functional properties of eDCs and resident LCs in different clinical phases of psoriasis, and the capacity of these cells to amplify the epidermal microenvironment through the secretion of IL-17 polarizing cytokines.

Epidermal Th22 and Tc17 cells form a localized disease memory in clinically healed psoriasis

Psoriasis is a common and chronic inflammatory skin disease in which T cells play a key role. Effective treatment heals the skin without scarring, but typically psoriasis recurs in previously affected areas. A pathogenic memory within the skin has been proposed, but the nature of such site-specific disease memory is unknown. Tissue-resident memory T (TRM) cells have been ascribed a role in immunity after resolved viral skin infections. Because of their localization in the epidermal compartment of the skin, TRM may contribute to tissue pathology during psoriasis. In this study, we investigated whether resolved psoriasis lesions contain TRM cells with the ability to maintain and potentially drive recurrent disease. Three common and effective therapies, narrowband-UVB treatment and long-term biologic treatment systemically inhibiting TNF-α or IL-12/23 signaling were studied. Epidermal T cells were highly activated in psoriasis and a high proportion of CD8 T cells expressed TRM markers. In resolved psoriasis, a population of cutaneous lymphocyte-associated Ag, CCR6, CD103, and IL-23R expressing epidermal CD8 T cells was highly enriched. Epidermal CD8 T cells expressing the TRM marker CD103 responded to ex vivo stimulation with IL-17A production and epidermal CD4 T cells responded with IL-22 production after as long as 6 y of TNF-α inhibition. Our data suggest that epidermal TRM cells are retained in resolved psoriasis and that these cells are capable of producing cytokines with a critical role in psoriasis pathogenesis. We provide a potential mechanism for a site-specific T cell-driven disease memory in psoriasis.

Multiparameter phenotyping of T-cell subsets in distinct subgroups of patients with pulmonary sarcoidosis

OBJECTIVES

  Sarcoidosis is an inflammatory disorder in which elevated numbers of activated T cells are found in the lung. HLA-DRB1*0301(pos) (DR3(pos) ) patients are characterized by good prognosis and an accumulation of lung CD4(pos) T cells expressing the T-cell receptor (TCR) gene segment AV2S3. Our aim was to phenotype lung and blood T-cell subsets in distinct patient groups to better understand the function of these subsets.

DESIGN

  Bronchoalveolar lavage (BAL) fluid and whole blood were obtained from a total of 22 patients with sarcoidosis, of whom 11 were DR3(pos) . Using eight-colour flow cytometry, phenotyping of T cells was performed with regard to CD3, CD4, CD8, CD25, CD27, CD45RO, CD57, CD69, CD103, FOXP3 and TCR AV2S3.

RESULTS

  DR3(pos) patients had fewer FOXP3(pos) (regulatory) CD45RO(pos) (memory) BAL T cells than DR3(neg) patients. Fewer AV2S3(pos) T cells were FOXP3(pos) , compared with AV2S3(neg) cells, thus indicating an effector function and not a regulatory role for this subset. Fewer lung and blood AV2S3(pos) T cells were CD25(pos)  CD27(pos) , and more were CD25(neg)  CD27(neg) and CD69(pos) , compared with AV2S3(neg) T cells, indicating a higher degree of differentiation and activation in both compartments.

CONCLUSION

  Our main findings were a lower proportion of regulatory T cells in DR3(pos) patients, together with the accumulation of AV2S3(pos) T cells with a highly activated effector phenotype in the lungs of these patients. This may provide for efficient elimination of a harmful antigen in DR3(pos) patients and could thus help to explain the spontaneous recovery typically seen in these patients.

Antigen-specific multifunctional T-cells in sarcoidosis patients with Lofgren's syndrome

Sarcoidosis is a granulomatous disease of unknown aetiology, mainly affecting the lungs. Recently, T-cell responses towards a specific mycobacterial protein, catalase-peroxidase (mKatG), were observed in sarcoidosis patients. Bronchoalveolar lavage (BAL) fluid and peripheral blood were obtained from a total of 23 sarcoidosis patients, of whom 13 had Löfgren's syndrome and lung accumulations of T-cell receptor AV2S3+ T-cells. Using six-colour flow cytometry in combination with intracellular cytokine staining, T-cell subsets were studied with regard to interferon (IFN)-γ, tumour necrosis factor (TNF) and interleukin-2 production, after stimulation with mKatG or Mycobacterium tuberculosis purified protein derivate (PPD). Stimulation with mKatG resulted in higher simultaneous IFN-γ and TNF production, but less single IFN-γ production, from total BAL fluid CD4+ T-cells of Löfgren's syndrome patients, when compared with non-Löfgren's patients. In contrast, PPD stimulation gave rise to largely similar cytokine responses in both patient subgroups. Furthermore, mKatG stimulated higher IFN-γ production in BAL fluid and blood AV2S3+ T-cells than AV2S3- T-cells, whereas the opposite was seen in BAL fluid with PPD stimulation. Our finding that patients with Löfgren's syndrome exhibited a more pronounced multifunctional cytokine profile (simultaneous IFN-γ and TNF production) towards the mycobacterial protein mKatG may help to explain the distinct disease presentation in this patient subgroup.

No evidence of altered alveolar macrophage polarization, but reduced expression of TLR2, in bronchoalveolar lavage cells in sarcoidosis

Background

Sarcoidosis is a granulomatous inflammatory disease, possibly of infectious aetiology. We aimed to investigate whether the degree of functional polarization of alveolar macrophages (AMs), or Toll-like receptor (TLR) expression, is associated with sarcoidosis or with distinct clinical manifestations of this disease.

Methods

Total BAL cells (cultured four or 24 h in medium, or stimulated 24 h with LPS) from 14 patients and six healthy subjects, sorted AMs from 22 patients (Löfgren's syndrome n = 11) and 11 healthy subjects, and sorted CD4+ T cells from 26 patients (Löfgren's syndrome n = 13) and seven healthy subjects, were included. Using real-time PCR, the relative gene expression of IL-10, IL-12p35, IL-12p40, IL-23p19, CCR2, CCR7, iNOS, CXCL10, CXCL11, CXCL16, CCL18, CCL20, CD80, and CD86, and innate immune receptors TLR2, TLR4, and TLR9, was quantified in sorted AMs, and for selected genes in total BAL cells, while IL-17A was quantified in T cells.

Results

We did not find evidence of a difference with regard to alveolar macrophage M1/M2 polarization between sarcoidosis patients and healthy controls. TLR2 gene expression was significantly lower in sorted AMs from patients, particular in Löfgren's patients. CCL18 gene expression in AMs was significantly higher in patients compared to controls. Additionally, the IL-17A expression was lower in Löfgren's patients' CD4+ T cells.

Conclusions

Overall, there was no evidence for alveolar macrophage polarization in sarcoidosis. However, there was a reduced TLR2 mRNA expression in patients with Löfgren's syndrome, which may be of relevance for macrophage interactions with a postulated sarcoidosis pathogen, and for the characteristics of the ensuing T cell response.

T cell responses to mycobacterial catalase-peroxidase profile a pathogenic antigen in systemic sarcoidosis

Sarcoidosis is a systemic granulomatous disease associated with local epithelioid granulomas, CD4(+) T cells, and Th1 cytokines. The tissue Ags that drive this granulomatous inflammation are uncertain. In this study, we used IFN-gamma-ELISPOT assays and flow cytometry to assess lung and blood T cell responses to the candidate pathogenic Ag, Mycobacterium tuberculosis catalase-peroxidase (mKatG) in patients with sarcoidosis from two centers. Despite differences in patient phenotypic, genetic, and prognostic characteristics, we report that T cell responses to mKatG were remarkably similar in these cohorts, with higher frequencies of mKatG-reactive, IFN-gamma-expressing T cells in the blood of sarcoidosis patients compared with nontuberculosis sensitized healthy controls, and (in a subset) in greater numbers than T cells reactive to purified protein derivative. In sarcoidosis, mKatG-reactive CD4(+) Th1 cells preferentially accumulated in the lung, indicating a compartmentalized response. Patients with or without Löfgren syndrome had similar frequencies of mKatG specific IFN-gamma-expressing blood T cells. Circulating mKatG-reactive T cells were found in chronic active sarcoidosis but not in patients with inactive disease. Together, these results demonstrate that T cell responses to mKatG in sarcoidosis fit a profile expected for a pathogenic Ag, supporting an immunotherapeutic approach to this disease.

Increased levels of nerve growth factor in the airways of patients with sarcoidosis

OBJECTIVES

Nerve growth factor (NGF) is a potent neuronal growth factor with inflammatory properties that recently has been proposed to be of importance in airway pathology. A role for NGF in the inflammatory granulomatous lung disease sarcoidosis is not well elucidated. The aims of this study were to investigate the secreted levels of NGF in bronchoalveolar lavage fluid (BALF) from sarcoidosis patients compared with patients with resolved disease, patients with another granulomatous disease--chronic beryllium disease (CBD)--and healthy subjects and also to investigate the relationship between NGF levels and markers of inflammation.

METHODS AND RESULTS

NGF levels in BALF from 56 patients with active sarcoidosis (22 with Löfgren's syndrome), nine subjects with resolved sarcoidosis, six patients with CBD, and 31 healthy subjects were compared. A 10-fold elevation of NGF levels was found in patients with active sarcoidosis compared with subjects with clinically resolved sarcoidosis, patients with CBD and healthy subjects. In sarcoidosis patients, positive correlations between concentrations of NGF and lymphocytes, eosinophils and interferon-gamma, interleukin (IL)-4, IL-10, IL-12 were found.

CONCLUSIONS

We demonstrate that secreted levels of NGF are markedly enhanced in the airways in active pulmonary sarcoidosis. Furthermore, a relationship between NGF and pulmonary inflammation in sarcoidosis is supported.

Reduced Th1 response in the lungs of HLA-DRB1*0301 patients with pulmonary sarcoidosis

To investigate why human leukocyte-associated antigen-DRB1*0301 (HLA-DRB1*0301) positive Scandinavian patients have a better prognosis than HLA-DRB1*0301 negative patients, the present authors examined patterns of cytokine expression in bronchoalveolar lavage (BAL) cells and BAL fluid (BALF) from patients with pulmonary sarcoidosis and controls. Using real-time PCR, the mRNA expression of selected cytokines in BAL cells from newly diagnosed, untreated nonsmoking patients (n=25) and controls (n=11) was quantified. Cytokine protein levels in BALF from patients (n=34) and controls (n=11) were assessed using cytometric bead array. The patients were evaluated and stratified into two subgroups: HLA-DRB1*0301 positive (all with an acute onset) and HLA-DRB1*0301 negative (all with an insidious onset). When comparing patients and controls, BAL cells of the patients expressed significantly higher levels of interferon (IFN)-gamma and interleukin (IL)-10 mRNA. There were significantly decreased IFN-gamma and tumour necrosis factor (TNF)-alpha mRNA levels, and a tendency toward higher levels of transforming growth factor-beta1 mRNA in HLA-DRB1*0301 positive compared with HLA-DRB1*0301 negative patients. Protein levels of IL-1beta, IL-2, IL-6, IL-12p70 and TNF-alpha in BALF were significantly higher in patients. HLA-DRB1*0301 positive patients exhibited tendencies to lower levels of most cytokines in BALF. In conclusion, the present data show a reduced expression of T-helper cell type-1 cytokines in human leukocyte-associated antigen-DRB1*0301 positive patients, which may relate to their good prognosis.

Ageing before mating and quinacrine ameliorate the expression of abnormal oocyte (abo) in homozygous Drosophila melanogaster females

Several studies have shown that the characteristically skewed sex ratio among the progeny of abo homozygous females, derived from heterozygous stocks and mated to attached XY males, can be modified during homozygous stock-keeping. This amelioration seems to have a complex mechanistic background, and both loss of the blood transposon from chromosome 2, where abo is located, and amplification of a specific heterochromatic element (ABO) have been suggested to work in this direction. There is also an increased frequency of non-disjunction associated with abo, beside the poor recovery of X0 males. Experiments were performed to see if there was a coordinated loss of both phenotypic expressions during homozygous stock-keeping and if non-disjunction was amenable to modification by quinacrine. We found an unexpected spontaneous amelioration of the phenotypic expressions of abo despite heterozygous stock-keeping. The spontaneous amelioration of non-disjunction and male lethality under heterozygous condition was coordinated while the process initiated by homozygosity slowly decreased non-disjunction and rapidly increased male recovery over generations, which may point to a mechanistic difference between the amelioration processes. Quinacrine was found to ameliorate the skewed sex ratio but did not affect non-disjunction. In these experiments larval and adult treatment, respectively, were employed and the respective controls revealed that also ageing before mating significantly increased male recovery and reduced non-disjunction. Ageing before mating and quinacrine seemed to act additively on male recovery, suggesting independent action, while interaction could be suspected between quinacrine and some ameliorating factor associated with brood. Some of the results also suggest that quinacrine acts indirectly and does not substitute for the abo gene product. Due to the action of quinacrine in other biological systems it is speculated that the compound compensates for a biochemical aberration in abo/abo females or their progeny, showing some relation to phospholipase activity and/or actin polymerisation state.

Enhancement of human B-cell proliferation by a monoclonal antibody to CD43

Monoclonal antibodies (MoAb) to human leucocyte sialoglycoprotein, CD43, have been shown to deliver mitogenic signals to human T cells or to enhance T-cell proliferation induced by concanavalin A, anti-CD3 antibodies or phorbol ester. In this paper, we studied the effects of anti-CD43 MoAb B1B6 on the activation of human B cells. Anti-CD43 MoAb B1B6 was not mitogenic by itself for human B cells. However, when added together with TPA, both resting and in vivo activated tonsillar B cells, containing 5-10% and about 35% CD43+ respectively, responded with three- to fivefold higher proliferation compared to that obtained with TPA alone. A peak in the proliferative response was reached on day 3. Optimal proliferation was obtained when the antibody was present from the start of culturing. Addition of MoAb B1B6 together with a calcium ionophore, ionomycin, did not induce B-cell proliferation. Neither did mAb B1B6 sustain the growth of B cells that were already in the cell cycle, i.e. precultured with phorbol ester (PDB) and ionomycin for 3 days. The results are similar to those obtained with antibodies to CD22 and CD23 and show that early progression signals are delivered to resting B cells through CD43 in the presence of primary activators of protein kinase C.

Studies on the role of CD43 in human B-cell activation and differentiation

The monoclonal antibody (MoAb) B1B6 to human leucocyte sialoglycoprotein, CD43, induces aggregation of T cells and delivers progression signals early during activation of both T and B cells in the presence of primary activators of protein kinase C. In this report we further studied the role of CD43 in human B-cell activation and differentiation. About 5-10% of resting tonsillar B cells are CD43+. In the presence of TPA or antibodies to CDw40, the proportions of CD43+ cells drastically increased. The expression was optimal on day 3 of culture, when up to 80% and 50%, respectively, were CD43+. Whereas MoAb B1B6 together with TPA induced a three- to fivefold higher proliferative response as compared to TPA alone, antibodies to CDw40 did not synergize with MoAb B1B6 in B-cell proliferation. Tonsillar populations depleted of CD43+ B cells responded with lower proliferation to TPA alone or to TPA and B1B6 or anti-CDw40 antibodies. MoAb B1B6 did not affect the production of IgM or IgG as induced by pokeweed mitogen in the presence of autologous T cells, from either peripheral blood or tonsillar B cells. Neither did it affect the IgG production from the CD43+ BSF-2 sensitive Epstein-Barr virus-transformed lymphoblastoid cell line CESS. The results show that CD43 is upregulated on B cells during activation. Furthermore, CD43+ B cells are included in the population which responds to signals delivered by TPA, anti-CD43 or anti-CDw40 antibodies, and the proliferation of this population is not merely due to an expansion of the small population of CD43+ cells present among these cells. Moreover, the epitopes recognized by MoAb B1B6 are not involved in the differentiation of and ultimate Ig-secretion from activated B cells.

Induction of CD43 expression during activation and terminal differentiation of human B cells

Only a small population (25-30%) of human peripheral blood B lymphocytes expresses large sialoglycoprotein (LSGP) (CD43). However, in the presence of autologous T cells and pokeweed mitogen (PWM) a majority (50-90%) of the immunoglobulin-producing cells (cIg+ cells) that develop from these B cells express CD43 is detected with anti-CD43 monoclonal antibodies (MoAb) B1B6, and the proportion of CD43+cIg+ cells increases with time of culture. Furthermore, a relatively larger proportion (60-80%) of the IgG-producing cIg+ cells are CD43+ compared with IgM-containing cIg+ cells (30-50%). In human tonsils, significantly more CD43+ cells (35%) are found in the in vivo-activated fraction of B cells than in the fraction of resting B cells (5%). A majority of the cIg+ cells that develop from the resting or the in vivo-activated tonsillar B cells in a PWM-induced B-cell differentiation system are CD43+ (80-100%). Furthermore, tonsillar B cells depleted of CD43+ cells give rise to cIg+ cells, of which the majority are CD43+, and the proportion of such cells increases with time of culture (60-90%). Taken together, these results indicate that LSGP belongs to a group of B-cell membrane molecules that are induced and upregulated upon activation and differentiation.

Functional characterization of human B cells carrying the lymphocyte large sialoglycoprotein gp150

Human B cell-enriched populations were prepared from buffy coats of healthy donors. By means of affinity chromatography, the B cells were separated into two fractions, one enriched in and the other depleted of cells expressing gp150, the large sialoglycoprotein of lymphocytes. In the presence of autologous T cells, monocytes and pokeweed mitogen B cell populations enriched for gp150+ cells gave rise to significantly more plasma cells (cIg+ cells) and secreted significantly more IgG than gp150-depleted populations. In contrast, more or an equal amount of IgM was secreted in cultures containing gp150-depleted cells. The differences between the fractions could not be ascribed to uneven distribution of T3+ cells, OKM1+ cells or B1+ (CD20) cells. However, the gp150-enriched population contained significantly more B2+ (CD21) cells than the gp150-depleted population. These results suggest that the gp150+ B cells differ from gp150- B cells, not only in their responsiveness to T cell differentiation signals but also in their commitment to Ig heavy chain isotype secretion.

Helper function of human T cells with different affinity for Helix pomatia A hemagglutinin in a tetanus toxoid-induced B cell differentiation system

T cells from human peripheral blood were enriched in T4+ cells by lysis of T8+ cells with the monoclonal antibody OKT8 plus complement. The T4+ subset was separated into 4 fractions differing in avidity for the lectin Helix pomatia A hemagglutinin (HP). The fractions were studied for their capacity to help autologous B cells to differentiate and mature into immunoglobulin (Ig) synthesis and secretion after activation with tetanus toxoid (TT) in vitro. To ensure the antigen specificity of induction, very low doses of TT (1-100 ng/ml) were used for activation of the lymphocytes, all obtained from previously sensitized donors. The T4+ cells with low avidity for HP (fractions HP-I and HP-II) exerted little help for B cell differentiation. Removal of these cells enhanced the helper function of the remaining T4+ cells, indicating that fractions HP-I and HP-II contained suppressor cells. In contrast, efficient B cell help was provided by T4+ cells with high avidity for HP (fractions HP-III and HP-IV). However, these fractions differed in the quality of help provided. Thus, while HP-III cells induced IgG secretion, HP-IV cells mainly induced IgM secretion. Moreover, while the Ig secreted after help from HP-III cells was TT-specific antibody, the Ig secreted by B cells in the presence of autologous HP-IV cells was polyclonal, probably reflecting induction of B cells differing in their responsiveness to signals provided by different types of T cells. The results indicate that T4+ cells vary in their stage of differentiation as seen by differences in expression of the HP marker and that differences in HP-marker expression appear to be associated with differences in cellular functions.

The use of supernatants from neuraminidase and galactose oxidase (NAGO)-treated lymphocytes as a source of T cell growth factor

Human peripheral blood or tonsil lymphocytes produce T cell growth factor (TCGF), when activated with neuraminidase (NA) and galactose oxidase (GO). Partial purification of NAGO-TCGF on Sepharose G-100 columns gave a TCGF-active fraction within the same molecular weight range as the conventional lectin-induced TCGF (approximately 15,000 Da). Human T cells, activated in mixed lymphocyte culture (MLC) with irradiated allogeneic EB-virus transformed B-cells (LCL) could be maintained in continuous culture for several months with retained functional activities. The cells showed similar growth patterns when cultured in the presence of either NAGO-TCGF or PHA-TCGF. The growing cells were characterized by means of monoclonal antibodies. After 4 weeks of culture 98% of these were OKT3+ and 87% were also OKT8+. The cytolytic activities of the cultures were tested in cell-mediated lympholysis (CML) against allogeneic LCL as target cells, in natural cytotoxicity (NK) against K562 cells and in antibody dependent cytotoxicity (ADCC) against bovine erythrocytes. Cultures displaying one or several of these functions were obtained. The results indicate, that TCGF obtained from supernatants of NAGO-activated lymphocytes is as potent as the T cell growth promoting factor obtained by lectin stimulation. One major advantage of using NAGO-generated TCGF is that contamination with lectin is avoided.