False-colour scannning electron micrograph of two T-lymphocyte killer cells (small cells),attacking a large cancer tumour cell. T-lymphocytes,white blood cells,must make intimate contact with the tumour cell. They do so by recognizing antigens on the tumour's surface. Following contact the tumour cell undergoes distinct structural changes; loss of microvilli (small projections,lost here),perforation & ultimately death. The tumour cell may survive,however,by budding off a number of blebs or blisters,which form a protective barrier between itself & the lymphocyte,preventing further contact. Magnification: X 2,500 at 35mm size |