Ultrastructural Analysis of Apoptosis Induced by the Monoclonal Antibody Anti-APO-1 on a Lymphoblastoid B Cell Line

Abstract

Apoptosis (programmed cell death) is the most common form of death in eukaryotic cells. We recently described a monoclonal antibody, anti-APO-1, which induces apoptosis of cells from the human B-lymphoblastoid line SKW 6.4 and of cells from a variety of other human lymphoid cell lines. This model of apoptosis was now studied ultrastructurally.

SKW 6.4 cells undergoing apoptosis showed the following morphological changes: condensation of the cytoplasm and karyoplasm, formation of large electron-opaque aggregates of the chromatin lining the nuclear membrane, “blebbing” of the cell membrane at an early stage of apoptosis, and dilatation of the mitochondria. Two hours after adding anti-APO-1, the nuclear membrane was ruptured. Occasionally, large vesicular enlargement of endoplasmic reticulum or Golgi appeared in the cytoplasm. Finally, total breakdown of all cell membranes and cellular disintegration was observed.

Key Words:

• apoptosis
• B-lymphoblastoid cells
• monoclonal antibody anti-APO-1
• ultrastructure