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Depletion of CD4 + CD25 + human regulatory T cells in vivo : Kinetics of Treg depletion and alterations in immune functions in vivo and in vitro
Author(s) -
Mahnke Karsten,
Schönfeld Kurt,
Fondel Sabine,
Ring Sabine,
Karakhanova Svetlana,
Wiedemeyer Katharina,
Bedke Tanja,
Johnson Theron Scott,
Storn Volker,
Schallenberg Sonja,
Enk Alexander Herrmann
Publication year - 2007
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.22617
Subject(s) - immune system , in vivo , cd8 , il 2 receptor , immunology , antigen , biology , effector , t cell , microbiology and biotechnology , chemistry
The aim of this study was to investigate whether depletion of CD4 + CD25 + regulatory T cells (Treg) from melanoma patients affects immune responses against tumors. By application of recombinant IL‐2‐diphteria toxin fusion protein, also known as ONTAK, we were able to significantly reduce the frequency of Treg in peripheral blood, whereas other cell populations remained unaffected. The reduction of Treg started immediately after the first bolus of ONTAK with a dose of 5 μg ONTAK per kg bodyweight and lasted for 13 days with subsequent recovery thereafter. Successive ONTAK treatments further reduced the number of circulating Treg. Using the contact sensitizer DCP we show that all patients developed vast eczema after Treg depletion, whereas no or only mild eczematous reactions were detectable before ONTAK treatment. Corresponding induction of DCP‐specific CD4 + and CD8 + T cells were detectable. Moreover, after immunization of ONTAK treated patients with tumor antigen peptides, MelanA/MART‐1 and gp100, significant induction of peptide specific CD8 + T cells could be observed in 90% of the patients treated. These cells displayed effector functions, as they were able to lyse peptide‐pulsed target cells and secreted IFNγ upon restimulation. In aggregate, our data indicate that ONTAK depletes Treg in vivo significantly, resulting in enhanced immune functions and substantial development of antigen‐specific CD8 + T cells in vaccinated individuals. © 2007 Wiley‐Liss, Inc.