Submitted November 6, 2006
Accepted December 3, 2007
Expansion of immunoglobulin autoreactive T-helper cells in multiple myeloma
Masih Ostad, Margareta Andersson, Astrid Gruber, and Anne Sundblad*
Department of Medicine, Division of Hematology, Karolinska Institutet and University Hospital, Stockholm, Sweden
* Corresponding author; email: anne.sundblad{at}ki.se.
Activation and expansion of T helper (Th)-cells followed by regulation of activation, are essential to the generation of immune responses while limiting concomitant autoreactivity. In order to characterize T cells reactive towards myeloma derived monoclonal immunoglobulin (mIg), an autologous co-culture assay for single-cell analysis of mIg-responding cells was developed. When cultured with dendritic cells loaded with mIg, CD4+ Th-cells from patients with multiple myeloma (MM) showed a proliferative MHC class II-dependent response. CD8+ T cell reactivity and Th1-activation were consistently low or absent and Th2- and regulatory cytokines were expressed. The presence of such non-Th1 CD4+ T cells in peripheral blood was independent of treatment status, while the frequencies of responding cells varied between patients and reached the same order of magnitude as those measured for tetanus toxoid-specific Th memory cells. Furthermore, investigations of T cell subpopulations indicated a possible regulatory role on the mIg-responsiveness mediated by suppressive CD25highFOXP3+CD4+ T cells.
It is proposed from the present results that a predominant in vivo activation of non-Th1 mIg-reactive CD4+ T cells constitute an Ig-dependent auto-regulatory mechanism in human MM, with possible tumour growth supporting or permissive effects.
