Lymphocyte proliferation kinetics in malnourished children measured by differential chromatid staining.

1. Utilizing the bromodeoxyuridine differential-chromatid labelling technique the in vitro proliferation of lymphocytes from children with kwashiorkor was followed in phytohaemagglutinin-stimulated cultures and compared with controls. 2. Analyses of first, second and third or subsequent division cells as a function of culture time between 40 and 96 h showed that cell-cycle duration was prolonged in kwashiorkor cultures. The extent of this increase was approximately 4.5 h for the first-division cells and 1.5 h for third-division cells. 3. The peak for second-division cells was depressed in kwashiorkor cultures. 4. A decreased number of third or subsequent-division cells was observed in kwashiorkor cultures at all time points studied. 5. These findings suggest that the loss in lymphocyte activity to PHA in malnourished children in general could be due to an increase in cell-cycle duration of responding lymphocytes.