J ALLERGY CLIN IMMUNOL

FEBRUARY 2013

AB196 Abstracts

MONDAY

699 Persistent Hypogammaglobulinemia After RituximabTreatment

Yelena Kopyltsova, MD1, Blanka M. Kaplan, MD, FAAAAI2, Vincent R.

Bonagura, MD, FAAAAI3; 1North Shore LIJ, Great Neck, NY, 2Cohen

Children’s Medical Center of New York, Great Neck, NY, 3Hofstra, North-

shore-LIJ School of Medicine, Great Neck, NY.

RATIONALE: Rituximab is an anti-CD20 chimeric antibody used to treat

blood malignancies and autoimmune disorders. B-cells usually recover

within six to twelve months after rituximab administration. Few cases of

persistent hypogammaglobulinemia after rituximab have been reported.

METHODS: We describe 12 patients with persistent hypogammaglobu-

linemia after rituximab. Rituximab was used for treatment of various

autoimmune disorders and lymphomas.

RESULTS: 90% of patients presented with recurrent infections (sinusitis,

skin infections, MRSA bacteremia, pneumonias, c. difficile colitis, 1 case of

endocarditis, 1 case of periorbital cellulitis). All patients had decreased IgG

levels (117-500, mean 387). Non-protective titers were 80% for pneumo-

coccal vaccine, 50% for tetanus, 30% for diphtheria. 75% of patients were

started on IVIG. 18% of patients had undetectable (<2) B-cells post

rituximab (24-72 months, mean 48). In 73% of patients B-cells returned to

normal 6-27 months after Rituximab treatment (mean 16 months).

CONCLUSIONS: We present a case series of twelve patients with

protracted hypogammaglobulinemia after rituximab. The majority of these

patients had recurrent infections, delayed recovery of B-cell number and

function, and required IVIG treatment. Therefore, rituximab may lead to

prolonged and possibly persistent B-cell deficiency. We hypothesize that

patients with persistent infections and hypogammaglobulinemia after

rituximab may have preexisting immune dysfunction. It may be prudent

to obtain baseline B-cells and immunoglobulin levels prior to starting

treatment with rituximab andmonitor as clinically indicated. * Three of the

twelve patients were previously reported in ACAAI meeting.

700 Thymus Transplantation Restores the Repertoire of Foxp3+ TCells in Complete DiGeorge Anomaly

Ivan Chinn, MD1, Joshua D. Milner, MD2, Phillip Scheinberg3,4, Daniel

Douek4, M. Louise Markert, MD, PhD, FAAAAI1; 1Duke University

Medical Center, Durham, NC, 2National Institute of Allergy and Infec-

tious Diseases (NIAID), Bethesda, MD, 3National Heart, Lung, and Blood

Institute, Bethesda, MD, 4National Institute of Allergy and Infectious Dis-

eases, Bethesda, MD.

RATIONALE: The importance of thymic function for establishing the

repertoire ofFoxp3+Tcells inhumanshasnot been fully explored.Wehypoth-

esized that infants with athymia from complete DiGeorge anomaly (cDGA)

could spontaneously form Foxp3+ T cells before thymus transplantation.

METHODS: Seven infants with cDGA and pretransplantation T cell clones

were assessed. Five of the 7 subjects developed pretransplantation Foxp3+ T

cells, but the cells did not suppress autoimmunity (rash and lymphadenopa-

thy). The effects of thymus transplantation were studied in 2 subjects.

RESULTS: In both subjects, pretransplantation Foxp3+ CD4+ T cells

showed low T cell receptor variable b chain (TCRVb) repertoire diversity,

mismatched from the repertoires ofCD4+T cells as awhole. Testing for clon-

ality showed that pretransplantation Foxp3+ and Foxp3– CD4+ T cells shared

16 unique TCRBVDNA sequences, accounting for 60% of sequences identi-

fied. This finding suggested that Foxp3+ cells were induced and amplified

from Foxp3– T cells. Posttransplantation, thymus graft function was con-

firmed through naive T cell production. Foxp3+ and total CD4+ T cells devel-

opeddiverse,matchingTCRVb repertoiresby16months posttransplantation,

associated with successful discontinuation of immunosuppression. TCRBVsequence sharing between Foxp3+ and Foxp3– CD4+ T cells diminished sub-

stantially to 1% of sequences identified. The pretransplantation Foxp3+ T

cells clones became nearly undetectable: only 2 pretransplantation Foxp3+

T cell TCRBV sequences were found posttransplantation.

CONCLUSIONS: Thus, whereas the repertoires of pretransplantation

Foxp3+ T cells were inadequate for suppressing autoimmunity, posttrans-

plantation thymic function was important for establishing improved reper-

toires of Foxp3+ CD4+ T cells, associated with clinical recovery.

701 Immunotolerance Mechanisms Depend On High Vs Low Doseof Sublingual Immunotherapy

Kari Nadeau, MD, PhD, FAAAAI1, Soujanya Vissamsetti, MD2; 1Stan-

ford University School of Medicine, 2Stanford University.

RATIONALE: Even after 100 years of use, the optimal dose and details on

the immune mechanisms behind successful allergen-specific immunother-

apy remain unclear.

METHODS: To determine the most effective dose for sublingual immu-

notherapy (SLIT) and to investigate the immune mechanisms involved in

successful SLIT.We performed a phase 1, single-site, randomized, double-

blind, placebo-controlled trial in timothy grass(TG)-allergic adults com-

paring treatment in three arms: placebo vs. low dose TG SLIT at 15 mcg

daily vs. high dose TG SLIT at 150 mcg daily. Efficacy, clinical tolerance

induction, and immune parameters were assessed throughout the 18-month

study.

RESULTS: Our results demonstrate that memory Treg are induced in

subjects that undergo tolerance induction during low dose TG SLIT,

whereas IFNg+ Th1 T cells predominate in tolerant subjects receiving high

dose TG SLIT. Both active treatment arms resulted in better clinical

outcome (P < 0.0001 for HD, P < 0.005 for LD) and increased TG-specific

IgG4 as compared to placebo; however, only subjects on high dose TG

SLIT sustained the increased levels of IgG4 over time (P < 0.05). In

addition, T cells from tolerant subjects on both high and low dose TG SLIT

demonstrated epigenetic modifications of loci important for Th1 or Treg

regulation, respectively.

CONCLUSIONS: HD allergen-specific SLIT results in immune modu-

lation of Th1 cells at the DNA level that may lead to more successful

therapy in the long-term.

702 Mechanisms of Th2 to Treg Vs Th2 to Th1 in Non Rush Vs RushFood OIT

Shu-Chen Lyu1, Kari Nadeau, MD, PhD, FAAAAI2; 1Stanford Univer-

sity, 2Stanford University School of Medicine.

RATIONALE: Food allergy is a significant health concern, with preva-

lence rates rising dramatically over the past decade. One of the most

promising therapies is oral immunotherapy (OIT). The current study

investigates the role of regulatory T cells (Treg) vs. Th1 cells in the

immune mechanisms involved in ‘‘tolerance’’ or sustained unresponsive-

ness induction during OIT.

METHODS: Peanut allergy subjects received either peanut OITor peanut

OITwith omalizumab. At 24 months, desensitized patients were identified

with a double blind placebo controlled food challenge (DBPCFC) and

abstained from treatment for 3 months followed by DBPCFC at 27 months

to identify immune tolerant subjects. T cell populations from allergic

patients undergoing therapy were analyzed for phenotype, functional

suppression of allergen-specific responses, and genetic profile to assess the

immune mechanism of tolerance induction.

RESULTS: Immune tolerant subjects on non rush (OITwithout omalizu-

mab) demonstrated an increase in suppressive, IL-10+ or Forkhead Box P3

(Foxp3)+ induced Tregpopulations at the 27 month time point whereas im-

mune tolerance subjects on rush (OITwith omalizumab) demonstrated an

increase in IFN-gamma producing T effector cells. Differential methyla-

tion of CpG sites within Foxp3 and IL-10 and IFN-gamma were observed

between immune tolerant subjects undergoing non rush vs rush OIT.

CONCLUSIONS: Our data demonstrate that Foxp3+ induced memory

Treg vs. Th1 cells were the key cell types modulating effector T cell re-

sponses during the course of non rush OIT vs. rush OIT, respectively, in

‘‘immune tolerant’’ subjects.