AuthOr’s VIew

The degree and the composition of lym-phocytes infiltrating human malignant tumors have strong positive prognostic relevance.1 Most studies performed so far focused on the cell type with best anti-tumoral potential, i.e., CD8+ T cells. However, when tumor-infiltrating B cells (TiBcs) were analyzed, their presence was frequently found to be the next-best predictor of positive disease outcomes.2 In addition to their antibody (Ab)-producing capacity, TiBcs boost T-cell responses via stimulatory cytokines and chemokines, by serving as local antigen-presenting cells, and form tertiary lym-phoid structures in mutual cooperation with T cells and dendritic cells.3 In a classical dogma of tumor immunology, T-cell responses are considered to be good whereas humoral responses oppose the latter and are consequently bad. Decades of experimental work with inbreed mouse strains have support this point of view. However, novel clear cut data from the fields of autoimmunity and transplanta-tion demonstrate the extremely strong tissue damaging potential of B cells, espe-cially when they interact with T cells. Thus, as far as B cells are concerned, we see the above outlined dogma breaking into parts. Breast cancer is the tumor entity in which TiBcs have been best analyzed, their presence being a clear positive prognos-tic factor.4 In this setting, tumor antigen Tumor-infiltrating B cells The ignored players in tumor immunolog