Immunosuppression in Burkitt's lymphoma. II. Peripheral blood lymphocyte populations related to clinical status.

We have studied peripheral blood lymphocyte populations, defined in terms of their E and EAC' rosette-forming capacity in patients with Burkitt's lymphoma and controls. Total lymphocyte counts were reduced in patients compared to controls (p less than 0.005), and correlated with clinical stage and disease status. Presenting patients with Stage D tumours had the lowest levels, while patients in remission for at least 18 months had total lymphocyte counts similar to those of controls. Absolute numbers of both E and EAC' rosette-forming cells (RFC) were reduced, compared to controls, in tumour-bearing patients (p less than 0.0005 for both E and EAC' RFC) and also, to a lesser extent, in patients in remission (p less than 0.025 and less than 0.05 for E and EAC' RFC respectively). In the case of E RFC a significant reduction was present even when patients in remission for over 18 months were considered alone (p less than 0.05). Non-RFC were present in similar numbers in patients and controls, so that the reduction in total lymphocyte count can be accounted for entirely by the reduced numbers of RFC. As anticipated by this, percentages of RFC were also reduced in patients compared to controls, EAC' RFC to a lesser extent than E RFC. Non-RFC percentages were correspondingly increased. Tumour-bearing patients had significantly impaired PHA responses and cutaneous reactivity, which correlated significantly with very low levels of RFC. One possible explanation for these results is that immunoreactive lymphocytes are sequestered within the tumour. This is consistent with the immunosuppression observed in tumour-bearing patients, and would also result in difficulty in detecting even a powerful tumour-specific immune reaction by means of an assay dependent upon the participation of peripheral blood lymphocytes.