Animal models of atherosclerosis suggest that B cells have contradictory protective or proatherogenic effects that are also subset and context dependent. To further understand the pathophysiology of human atheroma, we characterized local Ig production and functional properties of resident B cells in human arterial lesions. Ig repertoires were analyzed by RT-PCR in carotid endarterectomy samples. Cytokine, differentiation marker and transcription factor mRNA expression was studied on arterial wall lymphocytes isolated by laser capture microdissection. Ig sequence analysis revealed that individual samples each contained a limited number of B cell clones. Functional α and γ mRNAs made up the majority of H chain mRNAs in the adventitia. Clonal evolution of Ig V regions, expression of activation-induced cytidine deaminase, clonal H chain switch, and an inverted λ/κ ratio of Ig L chain usage indicated that a local differentiation process was taking place in arterial walls. Clonotypic markers revealed different plaque and adventitia Ig repertoires and a B cell recirculation between adventitia and draining lymph nodes. Microdissected mononuclear cells had an activated phenotype expressing IL-6, GM-CSF, and TNF-α, whereas IL-2, IL-4, IL-10, M-CSF, and IFN-γ were not detected. Adventitial oligoclonal resident B cells of atherosclerotic patients are mainly mature B2 (conventional) CD20− plasmablasts lacking markers of terminal differentiation to plasma cell (CD138 and Blimp-1). They present hallmarks of Ag-driven maturation and could act on inflammation and disease progression directly or by promoting polarization of other immune cells.

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The multifunctional growth factor mannose-6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2-R) binds proteins sharing M6P signals, including cathepsins and IGF2. It is involved in targeting newly synthesized mannose-6-phosphorylated lysosomal enzymes, activating transforming growth factor beta (TGFbeta), and neutralising the mitogen IGF2 by transporting it to lysosomes. The M6P/IGF2-R was proposed as being coded by a tumor suppressor gene. We measured gene expression at the protein level by quantitative immunohistochemistry, using chicken high affinity IgY antibodies directed against human M6P/IGF2-R. Chicken immunization was performed with human purified M6P/IGF2-R, and IgY antibodies were extracted from egg yolk by polyethylene glycol precipitation method. The biosensor analysis showed that IgY antibodies bind M6P/IGF2-R with high affinity (Kd = 7.5 nM). Quantitative immunohistochemical studies in sections from invasive breast carcinoma and ductal carcinoma in situ (DCIS) indicated various levels (from 5 to 400 units) of the M6P/IGF2-R protein, which did not correlate with tumor size, histological grade, estrogen and progesterone receptors. Moreover, the M6P/IGF2-R level was increased in DCIS relative to adjacent normal tissue (p < 0.005) and then decreased in invasive carcinoma compared with DCIS (p < 0.02). The hypothesis of tumor suppressor gene is not supported by these studies. However, it is not excluded for a small proportion of the tumors. Its assay might help to complement the cathepsin D assay to predict breast cancer prognosis and physiopathology.

Thymidine phosphorylase (TP)/platelet-derived endothelial cell growth factor is associated with tumor angiogenesis. We evaluated the TP mRNA and protein expression in basal cell carcinomas (BCC) and in various skin tumors including numerous BCC histological simulants. Immunohistochemistry was performed on 99 paraffin sections of formalin-fixed skin tumors using monoclonal antibodies (mAb) against TP. TP mRNA levels were measured by real time RT-PCR in whole BCCs (wBCC) and laser capture microdissected (LCM) BCC tumor cells. TP immunostaining was negative in all BCC variants and in most of the benign trichogeneic tumors studied. By contrast, TP was constantly immunodetected in actinic keratosis (AK), squamous cell carcinomas (SCC), syringomatous carcinomas (SC), basosquamous carcinomas (BSC) and melanomas. TP mRNA levels were low and statistically not different in wBCC and normal skin but were strongly downregulated in LCM-BCC as compared with LCM-normal epidermis. We concluded that (i) anti-TP mAb is an useful marker to differentiate BCC from AK, SCC, BSC and SC but not from trichoblastic tumors, (ii) the lack of TP protein expression in BCC tumoral cells is linked to transcriptional regulatory mechanisms, (iii) the low TP mRNA levels in whole BCC may be related to the low intra-tumoral microvessel density, the slow growth and the very low metastatic potential of these tumors.