In vitro characterization of immunological responsiveness of uremic patients.

Uremic patients are thought to have deficient immune reactivity. The mechanisms for immunosuppression are not known. We have studied various in vitro immune response parameters in lymphocytes from uremic patients and from healthy controls. Using polyclonal activating substances, it was found that PHA and LPS responses were reduced in cells from the patient group compared to the control group (p < 0.05). Furthermore, MLC responsiveness using pooled stimulator cells and polyclonal antibody secretion induced by Staphylococcus aureus bacteria in vitro were reduced in the patients (p < 0.05). No differences with regard to proportions of T/B cells in blood were noted between the two groups. No correlation was found between responses of individual cells to different activating substances, with the exception of PHA and ConA. However, low responses to PHA were usually accompanied by a general low responsiveness. Patients were further subdivided into groups according to the type of dialysis treatment, peritoneal dialysis (PD) or hemodialysis (HD), and to the duration of the hemodialysis period (< and > 1 year). Patients treated with PD showed impaired T cell reactivity with loer PHA responses compared to the HD patients (p < 0.05). Between the HD groups there were no significant differences in mitogen or MLC responses. We believe that the differences between PD and HD were due to the facts that the PD patients were older and not in the same nutritional state as the HD patients.