AB1151 DOES PREDNISONE AFFECT COVID19 VACCINE T CELL RESPONSE? A STUDY OF VACCINE RESPONSE IN PATIENTS WITH IMMUNE SYSTEM DISEASES

Background

A whole blood interferon gamma release assay (IGRA) based on the stimulation of SARS-Cov2-specific memory T cells using purified and full-lenght Spike and Nucleocapsid recombinant proteins was developed, together with anti-Spike antibody detection.

Objectives

To study COVID19 vaccine cellular and humoral responses in patients with immune system diseases (ISD) and healthy controls.

Methods

Non-vaccinated healthy individuals (n=103), SARS-Cov-2 infected individuals (n=9), and 104 samples from individuals having received COVID19 vaccine including 28 non-sars-cov2 infected patients with ISD diseases were included. Preliminary experiments were initiated using different platforms (ELISpot, IGRA, recombinant proteins or peptides) in order to evaluate Spike T cell response in volunteers vaccinated with BNT162b2 showing a S2>S1 poly-epitopic response.

Results

Twenty-eight patients (25 women, 3 men; mean age 59.1(±17,8)) with various ISD were investigated. These patients suffered from lupus (n=14), vasculitis (n=4), myositis (n=2), sarcoidosis (n=2), primary immunodeficiency (n=3), Sjögren’s syndrome (n=2) and pericarditis (n=1). Three patients had received 4 doses, 16 three doses, and 8 two doses of vaccine (Pfizer: n=25; Moderna n=1, Astra-Zeneca n=1). One patient refused the vaccination. The tests were performed 86.7 (±60.5) days after last vaccine dose. Ten patients were on prednisone (mean dose: 11,8 mg, median 7.5 mg, range: 5-40). Among those patients, 6 had only prednisone, 1 was also treated with belimumab, 3 with methotrexate (MTX) and 1 with azathioprine (AZA).

Following COVID19 vaccination, humoral (100% in healthy vs 84.6% in ISD patients) and IGRA-Spike T cell (96% in healthy vs 59.7% in AI patients) responses took place with lower response reported among the ISD disease group (Figure 1). Humoral and cellular COVID19 vaccine responses significantly decrease after 100 days post vaccine.

Figure 1.

SARS-Cov2 humoral and T cell responses in non-vaccinated healthy individuals (n=103), SARS-Cov-2 infected individuals (n=9), and 104 samples from individuals having received COVID19 vaccine including 28 non-Sars-cov2 infected patients with ISD diseases. A- Anti-SARS-Cov2 Spike total IgM/IgG/IgA antibody (Ab) titers (BAU/mL) tested by ELISA. B- Whole blood IFN-γ release assay (IGRA) response to the full-length Spike recombinant protein (IGRA-Spike). C- Whole blood IGRA response to the nucleocapsid recombinant protein (IGRA-Nuc). Positivity cut-off (dot line) p values <0.05 are indicated when significant (ANOVA).

5/5 vaccinated patients on CS alone, 2/5 vaccinated patients on corticosteroids with MTX/AZA/Belimumab and 3/17 other vaccinated patients (all being primary immunodeficiency patients) had no cellular response. Humoral and T cell responses were independent from sex and age.

Conclusion

Altogether, this ongoing study confirms the utility of the IGRA-Spike/-nucleocapsid assay coupled with serology in COVID19 vaccinated individuals and in particular in ISD patients treated with steroids, who may be at risk when the humoral protection decreases.

References

none

Disclosure of Interests

None declared

POS1178 PRESCRIBING RITUXIMAB IN PATIENTS WITH AUTO-IMMUNE DISEASES AND ACQUIRED HYPOGAMMAGLOBULINEMIA: DESCRIPTION OF THE RISK OF SEVERE INFECTION IN 121 PATIENTS BEFORE THE SARS-Cov2 ERA

Background

Rituximab (RTX) induces rapid, usually complete and prolonged depletion of circulating B cells, and also hypogammaglobulinemia in some patients. There are limited data regarding the risk of severe infection events (SIE) when initiating or continuing rituximab in patients with acquired hypogammaglobulinemia, especially in patients suffering from autoimmune diseases (ADs) other than rheumatoid arthritis (RA) (1).

Objectives

To describe the risk of severe infectious events (SIE) following initiation (rituximab-naïve patients [RNP]) or continuation of RTX therapy (rituximab-continuing patients [RCP]) in patients suffering from severe ADs other than RA and acquired hypogammaglobulinemia.

Methods

We conducted a single-center retrospective cohort study at the University Hospital of Toulouse (France) between 2010 and 2018. Patients were included if they had received at least one dose of RTX in the year following the evidence of hypogammaglobulinemia (defined as gammaglobulins [GG]≤ 6g/L on serum protein electrophoresis) in the setting of ADs other than RA. The primary outcome was the occurrence of a SIE within 2 years after the date of first RTX infusion (T0) prescribed after the evidence of hypogammaglobulinemia. SIE were infections either fatal or requiring hospitalization.

Results

We included 121 patients (37 RNP and 84 RCP): 48 had ANCA-associated vasculitis (AAV), 48 multiple sclerosis (MS, n=41) or neuromyelitis optica (NMO, n=7), and 21 another severe AD. RTX was prescribed as induction therapy in 39 patients and as maintenance therapy in 82; 112/121 patients were followed for 2 years. Mean GG level were 5.5 g/L (IQ25-75 4.6-5.7) at T0, 5.5 g/L (IQ25-75 5-6.4) at one year, 5.7g/L (IQ25-75 4.8-6.1) at two years and 8 patients had a decrease of their GG level below 4g/L. Ten patients received immunoglobulin replacement therapy (IGRT) mostly after infection (n=6).

Twenty-six patients (23.2%) had at least one SIE during follow-up: 12.8 % in the MS/NMO group with a 2-year incidence at 6.9 (3.1-15.3) per 100 person-years, 29.5 % in the AAV group with a 2-year incidence at 18.3 (9.3-20.1) per 100 person-years, 33.3 % in the ‘other ADs’ group with a 2-year incidence at 22.2 (10.6-46.5) per 100 person-years. Infection was opportunistic in 8 patients (33.3%) and 4 died from SIE.

Risk factors of SIE at T0 were male gender (61.5% vs. 39.5% p<0.05), lung disease (65.4% vs. 37.2% p=0.01), renal failure (59.1% vs. 28.6% p=0.01), a higher Charlson comorbidity index (p=0.001), a previous treatment by cyclophosphamide (53.8% vs. 30.2%; p=0.03), ≥ 5 mg/d prednisone (69.2% vs. 33.7%, p=0.003), lack of pneumococcal vaccination (61.5% vs 31.4%, p=0.01). GG level was 5.3 g/l [4.1-5.6] in the ‘SIE’ group vs 5.6 g/l [4.8-5.8] in the ‘no SIE’ group (p=0.04). Incidence of SIE was 46% and 20.2% among patients with GG< 4 g/L or GG≥ 4 g/L, respectively (p=0.07). No multivariable analysis provided reliable results.

Conclusion

Our study provides useful information for clinicians considering initiating or continuing rituximab therapy in patients with acquired hypogammaglobulinemia before Sars-Cov2 era. Prospective studies are necessary to improve the knowledge on outcome of patients treated by rituximab despite low immunoglobulins levels. Prophylactic IGRT may be appropriate in higher risk patients, especially if the GG level is below 4 G/L.

References

[1]Boleto G et al. Predictors of hypogammaglobulinemia during rituximab maintenance therapy in rheumatoid arthritis: A 12-year longitudinal multi-center study. Seminars in Arthritis and Rheumatism. oct 2018;48(2):149‑54.

Figure 1.

Two years probability of survival without serious infectious event according to pathology group (112 patients included)

Disclosure of Interests

None declared

T cell reconstitution after lymphocyte depletion features a different pattern of inhibitory receptor expression in ABO- versus HLA-incompatible kidney transplant recipients

Chronic antigen stimulation can lead to immune exhaustion (a state of T cell dysfunction). Several phenotypical signatures of T cell exhaustion have been described in various pathological situations, characterized by aberrant expression of multiple inhibitory receptors (IR). This signature has been barely studied in the context of allogenic organ transplantation. We undertook a cross-sectional analysis of the expression of IR [CD244, CD279, T cell immunoreceptor with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibition motif (ITIM) domains (TIGIT) and CD57] and their correlation with cytokine-producing functions in T cells reconstituting after lymphocyte depletion in patients transplanted from living donors, with preformed donor-specific antibodies. After ABO incompatible transplantation, T cells progressively acquired a phenotype similar to healthy donors and the expression of several IR marked cells with increased functions, with the exception of TIGIT, which was associated with decreased cytokine production. In stark contrast, T cell reconstitution in patients with anti-human leukocyte antigen (HLA) antibodies was characterized with an increased co-expression of IR by T cells, and specifically by an increased expression of TIGIT. Furthermore, expression of these receptors was no longer directly correlated to cytokine production. These results suggest that T cell alloreactivity in HLA-incompatible kidney transplantation drives an aberrant T cell reconstitution with respect to IR profile, which could have an impact on the transplantation outcome.

The importance of EN ISO 15189 accreditation of allergen-specific IgE determination for reliable in vitro allergy diagnosis

BACKGROUND

Allergen-specific serum immunoglobulin E detection and quantification have become an important step in allergy diagnosis and follow-up. In line with the current trend of laboratory test accreditation to international standards, we set out to design and assess an accreditation procedure for allergen-specific serum IgE.

METHODS

Method validation according to the accreditation procedure under the EN ISO 15189 standard was carried out for allergen-specific immunoglobulin E determination using the fluoroimmunoenzymatic method ImmunoCAP(®) (ThermoFisher). Data were produced by 25 hospital laboratories in France. A total of 29 allergen specificities including mixes, extracts, and molecular allergens were assayed. Allergen-specific serum immunoglobulin E concentrations ranged from 0.1 to 100 kUA /l.

RESULTS

Repeatability, reproducibility, and accuracy results fulfilled method validation criteria for automated laboratory tests and proved similar irrespective of the allergen specificity, allergen-specific serum immunoglobulin E concentration, or individual laboratory.

CONCLUSION

Allergen-specific serum immunoglobulin E determination with the fluoroimmunoenzymatic method ImmunoCAP(®) is a highly repeatable, reproducible, and accurate method which may be considered as a single analyte assay in view of the EN ISO 15189 accreditation procedure.

Innate mucosal-associated invariant T (MAIT) cells are activated in inflammatory bowel diseases

Inflammatory bowel diseases are characterized by a deregulated immune response targeting the gut bacterial flora. Mucosal-associated invariant T (MAIT) cells are major histocompatibility complex (MHC) class Ib-restricted innate-like lymphocytes with anti-bacterial functions. They display an effector/memory phenotype and are found in large numbers in the blood, mucosae and liver. They have also been implicated in inflammatory diseases such as multiple sclerosis. Therefore, we aimed to analyse the possible involvement of MAIT cells in Crohn's disease (CD) and ulcerative colitis (UC). To this end, a phenotypical and functional analysis of MAIT cells isolated from the blood of healthy subjects, CD and UC patients was undertaken. MAIT cells were also quantified in ileal biopsies of CD patients. The frequency of blood MAIT cells was specifically reduced in IBD patients compared with healthy donors, whereas it was dramatically greater in the inflamed versus healthy tissue. MAIT cells were activated as they expressed significantly more the Ki67 antigen, and this was accompanied by phenotypical changes such as increased expression of natural killer (NK)G2D and B and T lymphocyte attenuator (BTLA). Finally, in-vitro-activated MAIT cells from CD and UC patients secreted significantly more interleukin (IL)-17, together with a decreased interferon (IFN)-γ in CD but an increased IL-22 in UC. These data show that MAIT cells are activated in IBD, which results in an increased recruitment towards the inflamed tissues, an altered phenotype and a switch in the pattern of cytokine secretion. This is the first demonstration that MAIT cells are immune players in IBD, whose precise functions in this context need to be addressed.

An invariant T cell receptor alpha chain defines a novel TAP-independent major histocompatibility complex class Ib-restricted alpha/beta T cell subpopulation in mammals

We describe here a new subset of T cells, found in humans, mice, and cattle. These cells bear a canonical T cell receptor (TCR) alpha chain containing hAV7S2 and AJ33 in humans and the homologous AV19-AJ33 in mice and cattle with a CDR3 of constant length. These T cells are CD4(-)CD8(-) double-negative (DN) T cells in the three species and also CD8alphaalpha in humans. In humans, their frequency was approximately 1/10 in DN, 1/50 in CD8alpha+, and 1/6,000 in CD4(+) lymphocytes, and they display an activated/memory phenotype (CD45RAloCD45RO+). They preferentially use hBV2S1 and hBV13 segments and have an oligoclonal Vbeta repertoire suggesting peripheral expansions. These cells were present in major histocompatibility complex (MHC) class II- and transporter associated with antigen processing (TAP)-deficient humans and mice and also in classical MHC class I- and CD1-deficient mice but were absent from beta2-microglobulin-deficient mice, indicating their probable selection by a nonclassical MHC class Ib molecule distinct from CD1. The conservation between mammalian species, the abundance, and the unique selection pattern suggest an important role for cells using this novel canonical TCR alpha chain.