1. Normal lymphocytes show significant increases in their total LDH content and proportion of M-LDH during the first 24 hours of culture with PHA, while most of them undergo blast-cell formation in three days. The changes in LDH occur before mitosis is a factor in altering the cell population and apparently is the result of PHA action at the genetic loci controlling the synthesis of M- and H-LDH polypeptide subunits.
2. The capacity of lymphocytes from patients with CLL to produce blast-cells and to increase their total LDH activity and M-LDH content varied inversely with the height of the peripheral WBC counts. Sometimes prolongation of incubation to five days permitted LDH and blast-cell changes to become discernible. This perhaps resulted from increase by mitosis in the numbers of cells capable of reacting to PHA.
3. Increase in total LDH and proportion of M-LDH promotes glycolysis which may be needed to supply increased energy requirements for both blast-cell formation and mitosis.