Pyruvate kinase activity in the lymphocytes of malnourished, anergic patients

Intralymphocytic pyruvate kinase (PK) has been reported to have decreased activity in protein calorie malnutrition. We studied the activity of this enzyme in the lymphocytes of normal, nonhospitalized individuals (Group 1: n = 14) and malnourished, anergic patients on the surgical ward (Group 2: n = 17). The mean activity in Group 2 (0.12 ± 0.02 U/10⁷ cells) was significantly decreased (P < 0.001) from that in Group 1 (0.28 ± 0.03 U/10⁷ cells). Five of the patients in Group 2 were studied following return to normal skin reactivity and prior to discharge from hospital; their mean activity had returned to the normal range (0.32 ± 0.08; P < 0.005). Kinetic studies of the enzyme in normal, nonhospitalized controls (Group 3: n = 7) and malnourished, anergic patients (Group 4: n = 5) showed a significant reduction in V_max of Group 3 (0.51 ± 0.02 U/10⁷ cells) as compared to Group 4 (0.35 ± 0.03 U/10⁷ cells), P < 0.005, K_m in Group 4 showed a significant increase (1.59 ± 0.26 mM) as compared to Group 3 (0.71 ± 0.09), P < 0.005. These studies show that significant changes occur in intralymphocytic PK activity, V_max and K_m in the malnourished, anergic patient and suggest that examination of this enzyme may help to define the lymphocytes of malnourished, anergic patients.