The Ultrastructure of Phytohemagglutinin (PHA) Stimulated Lymphocytes of Chronic Lymphatic Leukemia

Cultured lymphocytes of chronic lymphatic leukemia have been shown to have a delayed and diminished response to phytohemagglutinin (PHA) stimulation. By electron microscopic examination, a morphologically distinct intermediate blastoid cell was identified in the stimulated cultures which showed minimal differences between those derived from normal and leukemic lymphocytes. It was distinguished by a large vesicular nucleus and relatively scant cytoplasm with few organelles. This intermediate blastoid cell frequently predominated in cultures with a low total percentage of blastogenesis. It is suggested that this intermediate blastoid cell represents a premitotic phase in lymphocytic transformation, though the possibility of it’s being a nonmitotic blastoid cell cannot be excluded. No morphologic differences were noted between the large blastoid cells transformed from normal and leukemic lymphocytes.