Specific reactivity of leukemia cells to polyclonal anti-PCB antibodies

Bivalve molluscs such as the soft shell clam (Mya arenaria) develop leukemias in the hemolymph which are fatal. The prevalence of leukemia in Mya was evaluated using a murine monoclonal antibody which recognizes a leukemia-specific protein expressed by tumor cells. The reactivity with a polyclonal antibody to polychlorinated biphenyls (PCBs) of both normal circulating cells and tumor cells was also determined. Both leukemia prevalence and PCB reactivity were ascertained by flow cytometry. Analytical chemistry was used to quantitate the amount of Aroclor per tumor cell population and compared directly to flow cytometric results. Our results show that the prevalence of leukemia consistently exceeds 60% when clams are retrieved from New Bedford Harbor, a site heavily contaminated with PCBs. Both normal circulating cells and tumor cells are extremely reactive with the PCB antibody. When clams from two other sites were compared with clams from New Bedford Harbor, both disease prevalence and cell reactivity to the PCB antibody were reduced. Our experiments are the first which use the flow cytometer to demonstrate PCBs in cell populations of marine invertebrates. Our results further demonstrate that the presence of polychlorinated biphenyls in vivo is directly correlated with environmentally linked leukemia.