Fractions of middle molecular weight responsible for immunodeficiency in malnourished and burnt patients.

Patients with protein calorie malnutrition (PCM) or burn injury have a high incidence of infection, partly related to a secondary deficiency of cell-mediated immunity. We have studied sera from 37 patients with PCM, 19 burns patients, and 8 uremic patients, and results were compared with those obtained in 12 healthy individuals. Chromatography on Sephadex G-25 fine revealed a high peak of so-called Middle Molecules. This fraction appeared to be almost superimposable on that separated from sera and urines of uremic patients, but even more concentrated especially in burns patients and in the severely hypoproteinemic patients with kwashiorkor. The proliferative responses of normal lymphocytes were inhibited by the patients' sera. A significantly more potent inhibition was obtained with middle molecular weight fractions from sera of these patients. Percentages of mixed lymphocyte reaction (MLR) inhibition were 69.38 +/- 21.69 (eluates from PCM patients), 67.05 +/- 21.75 (eluates from burnt patients), 66.37 +/- 31.38 (eluates from uremic patients), and 26.00 +/- 18.90 (eluates from control sera). Indirect evidence suggests that these inhibitory fractions may be responsible for several of the immunologic and hematologic disturbances found in PCM and in burnt patients.