Detection of tumor infiltrating B cells

Mullins et al. (Cancers, 2019) investigated the functionality of B cells in clinical tumor samples of patients with colorectal cancer.

The authors of the paper prove that the tumor infiltrating B cells are able to actively secrete immunoglobulins by performing an IgA, IgG and IgM FluoroSpot, now available as FluoroSpot Flex. The FluoroSpot technology enabled investigation of the functionality of cells directly isolated from the tumor. In detail, the researchers found more IgA than IgG and even less IgM secreting cells. Additionally, they discovered a correlation between IgG secretion with the number of MHCII expressing cells (= antigen-presenting cells, including B-cells) and noted that Ig secretion seems to be increased in primary tumors compared to metastases.

Altogether, these findings support the hypothesis that tumor infiltrating B cells have a dual function in antigen presentation and anti-tumor immunoglobulin production.