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Accumulating data are showing that the humoral immune response against tumors could favor tumor progression. However, no B lymphocyte pathology has been reported in cancer. Using anti-IgM Ab we nonspecifically depleted B cells in tumor-bearing mice, a treatment that resulted in significant reduction of tumor burden. We analyzed the B lymphocyte phenotype of abdominal lymph nodes and peripheral blood from advanced colon cancer patients by flow cytometry, and compared the B cell phenotype with that found in samples from normal donors. In both lymph nodes and peripheral blood of cancer patients, abnormal populations of B lymphocytes appeared that express an increased CD21 and/or sTn antigens on their cell surface. All patients showed a reduction of CD19+ cells. In a limited clinical test, we analyzed the effects of a partial B cell depletion with Rituximab. The treated patients did not develop any side-effects; the CD21-hyperpositive lymphocytes were reduced, but the proportion of sTn-positive lymphocytes remained unaffected. Apparent reduction of the tumor burden was reported in 50% of the patients when the treatment was ended.

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We report the pathology of benign and malignant skin lesions from 13 renal allograft recipients. The 59 lesions included 18 squamous carcinomas, 16 verrucous keratoses, 19 warts with varying dysplasia, three plaque lesions resembling those found in epidermodysplasia verruciformis, two non-specific keratoses and one basal cell carcinoma. We delineate criteria for histological assessment of the presence of human papilloma virus (HPV) and use the term verrucous keratosis for lesions in which there is a putative viral contribution. Our findings emphasize the lack of correlation between clinical and histological assessment of the lesions. We note the variable and significant dysplasia within otherwise typical viral warts and the architectural features suggestive of HPV presence in the dysplastic lesions and in in situ and invasive squamous carcinomas. Parallel virological studies have revealed the presence of HPV 5/8 in over 60% of the invasive and in situ carcinomas probed. These HPV types have previously been isolated from squamous carcinomas of epidermodysplasia verruciformis, a condition whose defective cell-mediated immunity may be compared with that of the immunosuppression in our patients.