Response of neoplasms of B cell lineage to the proliferative effects of B cell growth factor and the phorbol ester TPA.

Little information is available regarding the role of soluble growth factors in neoplastic B cell proliferation. The authors have measured B cell growth factor (BCGF)-induced proliferation in B lymphocytes isolated from 28 patients with malignancies representing different stages of B cell differentiation. The phorbol ester TPA (12-O-tetradecanoyl phorbol-13-acetate), a potent mitogen and inducer of BCGF receptor expression in normal B cells, was added in combination with BCGF to enhance the proliferative response. These results show that many neoplastic B cells are able to respond to BCGF (32%), particularly when combined with TPA (63%). The response was variable in frequency and magnitude within clinicopathologic groups; cells from patients with non-Hodgkin's lymphoma (NHL) were more refractory to stimulation than those from acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL). An attenuated response to BCGF plus TPA was observed in neoplastic cells with high rates of spontaneous DNA synthesis from all histologic categories. These observations suggest that some maximally stimulated cells appear incapable of responding to additional exogenous growth stimuli. Within apparently homogeneous clinicopathologic groups, distinct subgroups of B cell neoplasms can be defined by cellular responses to BCGF. The correlation of this biologic feature with the clinical behavior of the neoplasm requires additional study.