204 Marta I. Oliveira et al. Eur. J. Immunol. 2012. 42: 195–205 prepulsed with a mix of sAgs. Cell division was determined by the extent of CFSE dilution detected by ﬂow cytometry after 6 days of culture. Statistical analysis Statistical analysis was performed using Graphpad Prism soft- ware (Version 5.04 for Windows, Graphpad Software, La Jolla, CA, USA). Student’s unpaired t-test was used to analyze continuous data; a w2-test for independence was used to analyze noncontinuous data. Acknowledgements: The authors thank Simon Monard, IBMC, for cell sorting, Dr. Horejs´ı, Academy of Sciences of Prague, for providing anti-CD6 antibody MEM-98, and Dr. Marion Brown, University of Oxford, for the kind gift of the anti-CD6 antibody OX126, and for useful comments. This work was supported by the European Regional Development Fund (FEDER) through Programa Operacional Factores de Competitividade – COMPETE, and by the Portuguese Government through FCT – Fundac-a˜o para a Cieˆncia e a Tecnologia, projects PTDC/SAU- MII/64247/2006, PTDC/SAU-MII/98041/2008 and PEst-C/SAU/ LA0002/2011. M. I. O., C. M. G., A. M. S., and R. J. N. were recipients of studentships from FCT. C. Y. and S. J. D. are funded by the Wellcome Trust. M. P. is funded by Programa Cieˆncia 2007 (FCT), S. F. L. is funded by FCT-PTDC, M. A. A. C. was supported by a post-doctoral fellowship from FCT-POSI, S. F. was supported by the Ministe`re de l’Education Nationale et de La Recherche, and J. R. P. was supported by grant CA68675 from the National Institutes of Health. Conﬂict of interest: The authors declare no ﬁnancial or commercial conﬂict of interest. References 1 Aruffo, A., Melnick, M. B., Linsley, P. 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