Tumor-infiltrating T cells in primary cutaneous B-cell lympho-proliferative disorders.

Background: Tumor-infiltrating lymphocytes (TILs) are considered to play an important role in the antitumoral immune response. The presence and percentage of CD8-positive tumor-infiltrating T cells have been shown to correlate with differentiation and prognosis in various neoplasms. The aim of this study was to determine the number of CD8-positive T cells in various primary cutaneous B-cell lymphoproliferative disorders and to evaluate its correlation with the histological type of tumor.

Methods: Fifty-three lesions were examined by immunohistochemistry with antibodies targeting CD3, CD4, CD8 and TIA-1. Thirty-two lesions had been diagnosed as primary cutaneous B-cell lymphomas (CBCL) and 21 as B-cell pseudolymphomas (B-PSL). CBCLs included 15 follicular lymphomas (FL), 6 marginal zone lymphomas (MZL), and 11 diffuse large B-cell lymphomas (LCL). The number of CD8-positive cytotoxic T cells was determined by computer-assisted morphometrical microscopy.

Results: No significant difference could be detected in the density of CD8-positive T cells in B-PSL (101/105 microm(2)), FL (110/105 microm(2)), and MZL (122/105 microm(2)). In contrast, the number of CD8-positive cells (55/105 microm(2)) in LCL was significantly lower (p<0.01) compared to B-PSL, FL and MZL.

Conclusions: In summary the number of CD8-positive T cells in B-cell lymphoproliferative disorders differs in regard to tumor type and differentiation with lowest numbers in diffuse large B-cell lymphomas. However, due to an overlap of the number of TILs, this parameter cannot be employed as a diagnostic parameter for individual cases.