There is far less information available about the
tumor infiltrating B (TIL-B) cells, than about the
tumor infiltrating T cells. We focused on discovering the features and potential role of B lymphocytes in solid
tumors. Our project aimed to develop innovative strategies to define
cancer membrane structures. We chose two solid
tumor types, with variable to considerable B cell infiltration. The strategy we set up with invasive
breast carcinoma, showing medullary features, has been introduced and standardized in metastatic
melanoma. After detecting B lymphocytes by immunohistochemistry, VH-JH, Vκ-Jκ
immunoglobulin rearranged V region genes were amplified by RT-PCR, from TIL-B
cDNA.
Immunoglobulin variable-region genes of interest were cloned, sequenced, and subjected to a comparative
DNA analysis. Single-chain variable (scFv) antibody construction was performed in selected cases to generate a scFv library and to test
tumor binding capacity. DNA sequence analysis revealed an overrepresented VH3-1 cluster, represented both in the
breast cancer and the
melanoma TIL-B
immunoglobulin repertoire. We observed that our previously defined anti
GD3 ganglioside-binder antibody-variable region genes were present in
melanoma as well. Our
antibody fragments showed binding potential to disialylated
glycosphingolipids (
GD3 ganglioside) and their O acetylated forms on
melanoma cancer cells. We conclude that our results have a considerable
tumor immunological impact, as they reveal the power of TIL-B cells to recognize strong
tumor-associated
glycosphingolipid structures on
melanomas and other solid
tumors. As
tumor-derived
gangliosides affect immune cell functions and reduce the B lymphocytes' antibody production, we suspect an important B lymphocyte and
cancer cell crosstalk mechanism. We not only described the isolation and specificity testing of the tumor infiltrating B cells, but also showed the TIL-B cells' highly
tumor-associated
GD3 ganglioside-revealing potential in
melanomas. The present data help to identify new
cancer-associated
biomarkers that may serve for novel
cancer diagnostics. The two-direction regulation mechanism between immune B cells and the
tumor could eventually be developed into an innovative
cancer treatment strategy.