Kinetics of CD169, HLA-DR, and CD64 expression as predictive biomarkers of SARS-CoV2 outcome.

INTRODUCTION: Discriminating between virus-induced fever from superimposed bacterial infections is a common challenge in intensive care units. Superimposed bacterial infections can be detected in severe SARS-CoV2-infected patients, suggesting the important role of the bacteria in COVID-19 evolution. However, indicators of patients' immune status may be of help in the management of critically ill subjects. Monocyte CD169 is a type I interferon-inducible receptor that is up-regulated during viral infections, including COVID-19. Monocyte HLA-DR expression is an immunologic status marker, that decreases during immune exhaustion. This condition is an unfavorable prognostic biomarker in septic patients. Neutrophil CD64 upregulation is an established indicator of sepsis. METHODS: In this study, we evaluated by flow cytometry the expression of cellular markers monocyte CD169, neutrophil CD64, and monocyte HLA-DR in 36 hospitalized patients with severe COVID-19, as possible indicators of ongoing progression of disease and of patients' immune status. Blood testings started at ICU admission and were carried on throughout the ICU stay and extended in case of transfer to other units, when applicable. The marker expression in mean fluorescence intensity (MFI) and their kinetics with time were correlated to the clinical outcome. RESULTS: Patients with short hospital stay (≤15 days) and good outcome showed higher values of monocyte HLA-DR (median 17,478 MFI) than long hospital stay patients (>15 days, median 9590 MFI, p= 0.04) and than patients who died (median 5437 MFI, p= 0.05). In most cases, the recovery of the SARS-CoV2 infection-related signs was associated with the downregulation of monocyte CD169 within 17 days from disease onset. However in three surviving long hospital stay patients, a persistent upregulation of monocyte CD169 was observed. An increased neutrophil CD64 expression was found in two cases with a superimposed bacterial sepsis. CONCLUSION: Monocyte CD169, neutrophil CD64, and monocyte HLA-DR expression can be used as predictive biomarkers of SARS-CoV2 outcome in acutely infected patients. The combined analysis of these indicators can offer a real-time evaluation of patients' immune status and of viral disease progression versus superimposed bacterial infections. This approach allows to better define the patients' clinical status and outcome and may be useful to guide clinicians' decisions. Our study focused on the discrimination between the activity of viral and bacterial infections and on the detection of the development of anergic states that may correlate with an unfavorable prognosis.

Assessing SARS-CoV-2-specific T-cell reactivity in late convalescents and vaccinees: Comparison and combination of QuantiFERON and activation-induced marker assays, and relation with antibody status.

OBJECTIVES: Monitoring of SARS-CoV-2 spread and vaccination strategies have relied on antibody (Ab) status as a correlate of protection. We used QuantiFERON™ (QFN) and Activation-Induced Marker (AIM) assays to measure memory T-cell reactivity in unvaccinated individuals with prior documented symptomatic infection (late convalescents) and fully vaccinated asymptomatic donors (vaccinees). METHODS: Twenty-two convalescents and 13 vaccinees were enrolled. Serum anti-SARS-CoV-2 S1 and N Abs were measured using chemiluminescent immunoassays. QFN was performed following instructions and interferon-gamma (IFN-γ) measured by ELISA. AIM was performed on aliquots of antigen-stimulated samples from QFN tubes. SARS-CoV-2-specific memory CD4+CD25+CD134+, CD4+CD69+CD137+ and CD8+CD69+CD137+ T-cell frequencies were measured by flow cytometry. RESULTS: In convalescents, substantial agreement was observed between QFN and AIM assays. IFN-γ concentrations and AIM+ (CD69+CD137+) CD4+ T-cell frequencies correlated with each other, with Ab levels and AIM+ CD8+ T-cell frequencies, whereas AIM+ (CD25+CD134+) CD4+ T-cell frequencies correlated with age. AIM+ CD4+ T-cell frequencies increased with time since infection, whereas AIM+ CD8+ T-cell expansion was greater after recent reinfection. QFN-reactivity and anti-S1 titers were lower, whereas anti-N titers were higher, and no statistical difference in AIM-reactivity and Ab positivity emerged compared to vaccinees. CONCLUSIONS: Albeit on a limited sample size, we confirm that coordinated, cellular and humoral responses are detectable in convalescents up to 2 years after prior infection. Combining QFN with AIM may enhance detection of naturally acquired memory responses and help stratify virus-exposed individuals in T helper 1-type (TH1)-reactive (QFNpos AIMpos Abshigh), non-TH1-reactive (QFNneg AIMpos Abshigh/low), and pauci-reactive (QFNneg AIMneg Abslow).

COVID-19-Associated Pneumonia in a B-Cell-Depleted Patient With Non-Hodgkin Lymphoma: Recovery With Hyperimmune Plasma.

Coronavirus disease 2019 (COVID-19) can have a severe course in immunocompromised hosts and patients with hematological malignancies. In some cases, the bad prognosis is associated with the lack of B lymphocytes, with impaired antibody production and inefficient viral clearance. We report a case of a 67-year-old woman with a story of non-Hodgkin lymphoma treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone), who got a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection while being totally depleted of B cells. This condition has determined a severe and prolonged course of COVID-19, with persistently positive nasopharyngeal molecular swabs and lack of anti-SARS-CoV-2 specific antibodies. The clinical recovery was favored by the administration of convalescent hyperimmune plasma.

ESCCA/ISCCA protocol for the analysis of cerebrospinal fluid by multiparametric flow-cytometry in hematological malignancies.

Central nervous system (CNS) involvement is a serious but often underdiagnosed complication of hematological malignancies. Currently, the gold standard to detect CNS involvement is conventional cytology (CC) whose sensitivity though is lower than 50%. Multiparametric flow cytometry (MFC) demonstrated a superior sensitivity over CC, particularly when low levels of CNS infiltrating cells are present. Although prospective studies are few, a positive finding by MFC appears to anticipate an adverse outcome even if CC shows no infiltration. However, the use of MFC to diagnose CNS involvement presents some pitfalls, due to the typical hypocellularity of cerebrospinal fluids (CSF), and low cell vitality. Furthermore, the threshold to be used for defining the MFC positivity is not universally defined. In this paper, a working group of the European Society for Clinical Cell Analysis-ESCCA-and the Italian Society for Clinical Cell Analysis-ISCCA-will discuss the critical aspects of CSF processing, highlighting difficulties in storage and processing of samples, interpretation and reporting of data.

The ISCCA flow protocol for the monitoring of anti-CD20 therapies in autoimmune disorders.

BACKGROUND: Anti-CD20 monoclonals (MoAbs) are used in a variety of autoimmune disorders. The aim is to eliminate memory B cells sustaining the tissue damage and the production of pathogenic autoantibodies, while preserving naïve cells. The disappearance of memory B cells and the repopulation by naïve cells correlate with good clinical response, while the reappearance of memory B cells and plasmablasts correlates with relapse or resistance to therapy. Anti-CD20 induce extremely low B cell levels, requiring high-resolution techniques. The immune monitoring protocol developed by ISCCA is described and validated, to provide a standardized method for the clinical decision-making process during anti-CD20 therapies in autoimmune diseases. METHODS: A 10-marker, 8-color staining panel (CD20-V450, CD45-V500c, CD4-FITC + sIgM-FITC, CD38-PE, CD3-PerCP Cy5.5, CD19-PE-Cy7, CD27-APC, CD8-APC H7 + sIgG-APC-H7) is used to identify B cells, plasma cells/blasts, naïve and memory B cells, sIgM+ and sIgG-switched memory B cells, T and NK cells, with high-sensitivity analysis (>106 CD45+ cells). RESULTS: After an anti-CD20 dose, the B cell level is about zero in most patients. If B cells remain virtually absent (<0.1/µl), subsetting is not reliable nor meaningful. If B cells raise >0.3-0.5/µl, subsetting is possible and informative, acquiring >1.0-1.5 × 106 CD45+ events. Further testings can follow the quality of B cell repopulation. If B cells become detectable (>1/µl), the prevalence of memory B cells indicates non-responsiveness or a possible relapse. CONCLUSIONS: The ISCCA Protocol is proposed for a standardized prospective monitoring of patients with autoimmune disorders, to assist the safe and rational usage of anti-CD20 therapies.

Decrease of Non-Classical and Intermediate Monocyte Subsets in Severe Acute SARS-CoV-2 Infection.

In patients with severe SARS-CoV-2 infection, the development of cytokine storm induces extensive lung damage, and monocytes play a role in this pathological process. Non-classical (NC) and intermediate (INT) monocytes are known to be involved during viral and bacterial infections. In this study, 30 patients with different manifestations of acute SARS-CoV-2 infection were investigated with a flow cytometric study of NC, INT, and classical (CL) monocytes. Significantly reduced NC and INT monocytes and a downregulated HLA-DR were found in acute patients with severe SARS-CoV-2 symptoms. Conversely in patients with moderate symptoms NC and INT monocytes and CD11b expression were increased. © 2020 International Society for Advancement of Cytometry.

Naïve/Effector CD4 T cell ratio as a useful predictive marker of immune reconstitution in late presenter HIV patients: A multicenter study.

A significant proportion of HIV-infected patients experiencing a late diagnosis highlights the need to define immunological protocols able to help the clinicians in identifying patients at higher risk for immunological failure. The aim of the study was to evaluate the feasibility of easy cytometric tests in defining the effect of antiretroviral treatment (cART) on immunological homeostasis and in identifying predictive markers of early immune recovery. Chronic HIV infected patients (n = 202) were enrolled in a prospective multicentric study, and their immunological profile was studied before (w0) and after 24 weeks (w24) of antiretroviral treatment (cART) using a standardized flow cytometric panel. Based on CD4 T cell count before treatment, patients were divided in late (LP: CD4 <350/mmc), intermediate (IP: 350/mmc500/mmc) presenters. In all groups, cART introduction increased CD4 and CD4/CD8 T cell ratio, naïve T cell (CD4 and CD8) and CD127-expressing CD4 T cells. In parallel, cART significantly reduced effector memory T cells (CD4 and CD8) and T cell activation (CD38+CD8 and CD95+CD4 T cells). Moreover, the frequency of Naïve and Effector CD4 T cells before treatment correlated with several immune parameters key associated with the pathogenesis of HIV, thus mirroring the health of immune system. Interestingly, we identified the Naïve/Effector CD4 T cell ratio (N/EM) at w0 as a marker able to predict early immune recovery. Specifically, in LP, N/EM ratio was significantly higher in immunological responder patients (CD4>500/mmc at w24) when compared to immunological non responder (CD4 T cells <500/mmc at w24). Finally, a multivariate analysis indicates that after 24w patients with N/EM ratio higher than 1.86 at w0 recovered 96 CD4 T cells more than those with N/EM ratio lower than 0.46. Altogether, our data define an easy protocol able to define reliable immunological markers useful for the characterization of immune profile in viremic HIV patients and identify the naïve/effector CD4 T cell ratio as a new tool able to predict an early immune reconstitution potential.

Flow Cytometric Diagnosis of Paroxysmal Nocturnal Hemoglobinuria: Pearls and Pitfalls - A Critical Review Article.

Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare blood disorder characterized by chronic intravascular hemolysis, thromboses in unusual sites and cytopenias related to bone marrow failure. The diagnosis is based on the Flow Cytometric (FCM) detection of peripheral blood cell clones lacking the surface molecules linked to the GPI anchor, which is altered by mutations. Consensus studies have developed standardized and robust multicolor FCM assays to disclose PNH clones among red cells, neutrophils and monocytes at a high level of sensitivity and accuracy. High-resolution procedures have been also established to detect small PNH clones at a sensitivity level of around 0.01% in red cells and neutrophils. Cell clone type and size have been put into correlation with the clinical presentations of the associated diseases, and recommendations for the clinical follow-up have been established. The recent advent of the therapeutic monoclonal antibody Eculizumab has dramatically improved both the quality of life and the life expectancy of the affected patients, further increasing the importance of an accurate FCM detection and monitoring of the clones. The technical features of the FCM diagnostic workup and the many critical aspects of the analytical process are discussed here.

Efficacy of a strict surveillance policy towards inappropriateness of plasma transfusion.

BACKGROUND: Plasma transfusion is not without risks. Despite a limited spectrum of indications, plasma is frequently used as prophylaxis in non-bleeding patients, to correct altered coagulation tests. A high rate of inappropriate use of plasma transfusion is frequently reported, as well as underdosage. STUDY DESIGN AND METHODS: Since 2010 we started an education program that occurred in several phases to disseminate the knowledge of plasma transfusion guidelines. Since 2014 a 'zero tolerance' policy was applied: except for massive bleedings, plasma requests were prospectively evaluated, rejecting those without an appropriate indication. When indicated, at least 10 mL/Kg b.w.were issued. The previous five year period (2005-2009) served as control. RESULTS: The number of patients transfused/year decreased by 67.6% vs the control period (149 vs 460), and the liters of plasma issued/year decreased by 70.4% (233 vs 795). The deepest fall was observed in acute care wards (-70.8%). The mean volume transfused per episode raised from 731 mL ±â€¯70 to 879 mL ±â€¯154. The Prothrombin Time ratio at the moment of transfusion request increased from a mean of 1.35 (Interquartile range 1.20-2.64) in the control period to 1.62 (Interquartile range 1.43-1.98) in the last period (p < 0.001). CONCLUSION: With a proactive educational approach a remarkable reduction of plasma order and administration has been obtained, without any consequence on morbidity and mortality and with an estimated saving since 2014 of 750,000 €. A 'zero tolerance' policy can be effectively implemented only with a thorough workup with the local physicians, including repeated rounds of information and refreshing of the updated transfusion practice and knowledge of the established guidelines over the time.

Good's syndrome, a rare form of acquired immunodeficiency associated with thymomas.

Good's syndrome (GS) or thymomaassociated immunodeficiency is a rare clinical entity that should be ruled out in patients with thymoma who develop severe, recurrent bacterial infections and opportunistic viral and fungal infections. There are no treatment protocols established, hence, early recognition is imperative to avoid complications. We report the case of a 42-year-old female, known for a previous thymectomy for giant thymoma who has suffered for a long time from recurrent pulmonary and urinary tract infections and cold sores. In March 2016 she referred to our unit complaining of fever, cough, chest pain, and cold sores due to Herpes simplex virus (HSV), confirmed serologically as HSV-1. Chest X-ray showed left pneumonia due to Streptococcus pneumoniae. She started antibiotics (amoxicillin/clavulanic acid associated with azithromycin) with gradual improvement. Given her history she was studied for an underlying immunodeficiency: IgG, IgA, and IgM were significantly low or absent, as well as all IgG subclasses; blood and bone marrow aspirate leucocyte immunophenotyping showed complete absence of B lymphocytes and reduced CD4+ T cells. In light of: i) thymoma; ii) B lymphocyte deficit; iii) hypogammaglobulinemia; iv) recurrent infections, GS was diagnosed and pre-emptive immunoglobulin treatment, associated with HSV and Pneumocystis jiroveci prophylaxis (Acyclovir for HSV and Sulfamethoxazole- Trimethoprim for P. jiroveci) were started. Since then the patient has no longer presented any infectious episodes.

Features, reason for testing, and changes with time of 583 paroxysmal nocturnal hemoglobinuria clones from 529 patients: a multicenter Italian study.

In this study, we aimed at disclosing the main features of paroxysmal nocturnal hemoglobinuria (PNH) clones, their association with presentation syndromes, and their changes during follow-up. A large-scale, cooperative collection (583 clones from 529 patients) of flow cytometric and clinical data was entered into a national repository. Reason for testing guidelines were provided to the 41 participating laboratories, which followed the 2010 technical recommendations for PNH testing by Borowitz. Subsequently, the 30 second-level laboratories adopted the 2012 guidelines for high-resolution PNH testing, both upon order by the local clinicians and as an independent laboratory initiative in selected cases. Type3 and Type2 PNH clones (total and partial absence of glycosyl-phosphatidyl-inositol-anchor, respectively) were simultaneously present in 54 patients. In these patients, Type3 component was sevenfold larger than Type2 (p < 0.001). Frequency distribution analysis of solitary Type3 clone size (N = 442) evidenced two discrete patterns: small (20% of peripheral neutrophils) and large (> 70%) clones. The first pattern was significantly associated with bone marrow failure and myelodysplastic syndromes, the second one with hemolysis, hemoglobinuria, and thrombosis. Pediatric patients (N = 34) showed significant preponderance of small clones and bone marrow failure. The majority of PNH clones involved neutrophils, monocytes, and erythrocytes. Nevertheless, we found clones made exclusively by white cells (N = 13) or erythrocytes (N = 3). Rare cases showed clonal white cells restricted only to monocytes (6 cases) or neutrophils (3 cases). Retesting over 1-year follow-up in 151 cases showed a marked clone size increase in 4 cases and a decrease in 13, demonstrating that early breaking-down of PNH clones is not a rare event (8.6% of cases). This collaborative nationwide study demonstrates a clear-cut difference in size between Type2 and Type3 clones, emphasizes the existence of just two classes of PNH presentations based on Type3 clone size, depicts an asymmetric cellular composition of PNH clones, and documents the possible occurrence of changes in clone size during the follow-up.

Chronic Myeloid Leukemia With P190 BCR-ABL Translocation and Persistent Moderate Monocytosis: A Case Report.

Chronic myeloid leukemia (CML) with p190 BCR-ABL is rare. In some cases it is associated with peripheral monocytosis, while bone marrow shows features intermediate between CML and chronic myelomonocytic leukemia. The prognosis is controversial, but in the most recent literature p190 BCR-ABL CML seems associated with a poor outcome. We report a case of p190 BCR-ABL CML characterized by moderate monocytosis, without deep molecular response (DMR) to an initial imatinib treatment. After imatinib was replaced by dasatinib, a DMR was achieved, however without appreciable effects on monocytosis.

Multicenter validation of a simplified method for paroxysmal nocturnal hemoglobinuria screening.

BACKGROUND: Paroxysmal nocturnal hemoglobinuria (PNH) diagnostic guidelines recommend single-tube five- to six-color or two-tube four-color assays. PNH clones are detectable in only a fraction of patients at risk, and screening for new PNH cases can be complex and expensive. In this multicenter study, we have validated a simplified, one-tube two-color FLAER-based assay suitable for PNH screening. METHODS: Six laboratories received samples containing spiked PNH leukocyte clones to be analyzed in parallel with a common six-color cocktail (FLAER/CD24/CD45/CD64/CD15/CD14) and a simplified two-color mixture (FLAER/CD15), a shared calibration procedure, and a common analysis protocol. Replicate precision and sensitivity tests were performed on PNH patients, from undiluted to 1:10 000. Specificity tests were performed on normal donors to identify the possible sources of artifacts. RESULTS: The performance comparison between six-color and two-color assays showed an excellent agreement for granulocyte PNH clones. Dilution experiments showed an accurate detectability down to 0.01% sensitivity level for granulocyte PNH clones and to 1% for monocytes. Specificity experiments disclosed that basophils and platelets can contaminate the monocyte gate and generate false PNH events. CONCLUSIONS: A simplified two-color (FLAER/CD15) PNH screening test has been validated in a highly standardized multicenter study and proved feasible and effective in ongoing regional programs. Precision, sensitivity, and specificity of the simplified test for granulocytes were comparable to the more complex and expensive six-color assay and applicable for screening also in peripheral laboratories. The diagnostic confirmation of PNH should be always performed by a reference center using the established technique on all cell lineages.

Psychological Considerations in the Assessment and Treatment of Pain in Neurorehabilitation and Psychological Factors Predictive of Therapeutic Response: Evidence and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

BACKGROUND: In order to provide effective care to patients suffering from chronic pain secondary to neurological diseases, health professionals must appraise the role of the psychosocial factors in the genesis and maintenance of this condition whilst considering how emotions and cognitions influence the course of treatment. Furthermore, it is important not only to recognize the psychological reactions to pain that are common to the various conditions, but also to evaluate how these syndromes differ with regards to the psychological factors that may be involved. As an extensive evaluation of these factors is still lacking, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) aimed to collate the evidence available across these topics. OBJECTIVES: To determine the psychological factors which are associated with or predictive of pain secondary to neurological conditions and to assess the influence of these aspects on the outcome of neurorehabilitation. METHODS: Two reviews were performed. In the first, a PUBMED search of the studies assessing the association between psychological factors and pain or the predictive value of these aspects with respect to chronic pain was conducted. The included papers were then rated with regards to their methodological quality and recommendations were made accordingly. In the second study, the same methodology was used to collect the available evidence on the predictive role of psychological factors on the therapeutic response to pain treatments in the setting of neurorehabilitation. RESULTS: The first literature search identified 1170 results and the final database included 189 articles. Factors such as depression, anxiety, pain catastrophizing, coping strategies, and cognitive functions were found to be associated with pain across the various conditions. However, there are differences between chronic musculoskeletal pain, migraine, neuropathy, and conditions associated with complex disability with regards to the psychological aspects that are involved. The second PUBMED search yielded 252 studies, which were all evaluated. Anxiety, depression, pain catastrophizing, coping strategies, and pain beliefs were found to be associated to different degrees with the outcomes of multidisciplinary programs, surgery, physical therapies, and psychological interventions. Finally, sense of presence was found to be related to the effectiveness of virtual reality as a distraction tool. CONCLUSIONS: Several psychological factors are associated with pain secondary to neurological conditions and should be acknowledged and addressed in order to effectively treat this condition. These factors also predict the therapeutic response to the neurorehabilitative interventions.

Psychological Treatments and Psychotherapies in the Neurorehabilitation of Pain: Evidences and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

BACKGROUND: It is increasingly recognized that treating pain is crucial for effective care within neurological rehabilitation in the setting of the neurological rehabilitation. The Italian Consensus Conference on Pain in Neurorehabilitation was constituted with the purpose identifying best practices for us in this context. Along with drug therapies and physical interventions, psychological treatments have been proven to be some of the most valuable tools that can be used within a multidisciplinary approach for fostering a reduction in pain intensity. However, there is a need to elucidate what forms of psychotherapy could be effectively matched with the specific pathologies that are typically addressed by neurorehabilitation teams. OBJECTIVES: To extensively assess the available evidence which supports the use of psychological therapies for pain reduction in neurological diseases. METHODS: A systematic review of the studies evaluating the effect of psychotherapies on pain intensity in neurological disorders was performed through an electronic search using PUBMED, EMBASE, and the Cochrane Database of Systematic Reviews. Based on the level of evidence of the included studies, recommendations were outlined separately for the different conditions. RESULTS: The literature search yielded 2352 results and the final database included 400 articles. The overall strength of the recommendations was medium/low. The different forms of psychological interventions, including Cognitive-Behavioral Therapy, cognitive or behavioral techniques, Mindfulness, hypnosis, Acceptance and Commitment Therapy (ACT), Brief Interpersonal Therapy, virtual reality interventions, various forms of biofeedback and mirror therapy were found to be effective for pain reduction in pathologies such as musculoskeletal pain, fibromyalgia, Complex Regional Pain Syndrome, Central Post-Stroke pain, Phantom Limb Pain, pain secondary to Spinal Cord Injury, multiple sclerosis and other debilitating syndromes, diabetic neuropathy, Medically Unexplained Symptoms, migraine and headache. CONCLUSIONS: Psychological interventions and psychotherapies are safe and effective treatments that can be used within an integrated approach for patients undergoing neurological rehabilitation for pain. The different interventions can be specifically selected depending on the disease being treated. A table of evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation is also provided in the final part of the paper.

Different T cells' distribution and activation degree of Th17 CD4+ cells in peripheral blood in patients with osteoarthritis, rheumatoid arthritis, and healthy donors: preliminary results of the MAGENTA CLICAO study.

OBJECTIVE: To determine distribution of T cells and activation degree of Th CD4+ cells in peripheral blood of patients with osteoarthritis (OA), rheumatoid arthritis (RA), and healthy donors. METHODS: Patients with established diagnosis of RA according to American College of Rheumatology/European League Against Rheumatism 2010 criteria, knee or hip OA according to American College of Rheumatology criteria, and healthy blood donor volunteers were eligible. Multi-channel flow cytometry and monoclonal antibodies against CD3, CD4, CD8, CCR6, CD38, CXCR3, and HLA DR were used to distinguish and evaluate T cells' subpopulation. RESULTS: We analyzed blood samples of 15 patients with well-defined RA, 56 with hip or knee OA, and 20 healthy age matched controls. Blood samples from RA patients showed significantly higher counts of CD4+ CD38+ DR+ (activated CD4 T cells) and Th17 (CCR6+ CXCR3-) cells as compared to OA patients and control group (P<0.01). Furthermore the samples from the OA patients showed a higher percentage of activated CD4 T cells and Th17 cells as compared to control group (P<0.05). Interestingly there was no difference between Th1 (CD4+ CXCR3+ CCR6-) and Th2 (CD4+ CXCR3- CCR6-) between the three groups (P>0.1). CONCLUSION: According to the latest view of OA disease pathogenesis, our preliminary results support the hypothesis that OA may also be a disease with an immunological/inflammatory involvement like RA. It seems that there is a quantitative but non-qualitative difference in Th17 cells' profile, including the expression of activation markers, between RA and OA.