IL-7 mRNA is not overexpressed in mycosis fungoides and pleomorphic T-cell lymphoma and is unlikely to be an autocrine growth factor in vivo

Interleukin-7 (IL-7) is thought to be a growth factor for cutaneous T-cell lymphoma (CTCL) since it has been shown that IL-7 transgenic mice develop a cutaneous disorder characterized by enhanced T-cell proliferation with progression to malignancy and that in vitro growth of Sezary cell lines is IL-7 dependent, However, no direct in vivo evidence exists for the involvement of IL-7 in the pathogenesis of CTCL, Therefore, we examined IL-7 mRNA expression in skin biopsies from patients with mycosis fungoides (MF) (ii = 20) and pleomorphic T-cell lymphoma (it = 5), By semiquantitative RT-PCR, IL-7 mRNA was not detectable in any of the CTCL samples, or in normal human skin (it = 8) or in skin from patients with psoriasis (ii = 7) or atopic dermatitis (ii = 5), In contrast, IL-7 mRNA was detected in a biopsy from a kidney allograft transplant, in normal keratinocytes under various culture conditions and in several cell lines, Interestingly, using a highly sensitive nested PCR, IL-7 mRNA was detectable in all specimens tested, but there was no indication of IL-7 overexpression in MF when analysing lesions of patch, plaque or tumour stages, In contrast, increasing CD3 expression was found, which was most likely a consequence of the enhanced density of malignant T cells in advanced tumour stages, In summary, by the use of semiquantitative RT-PCR we were not able to detect IL-7 overexpression in MF or pleomorphic T-cell lymphoma, This indicates that IL-7 is probably not an autocrine growth factor in these CTCLs.