Mutations-induction followed by selection is a suitable method for developing a cell line with resistance to low doses of X-rays. In comparison with the original cell line, the derived resistant line is characterized by an enhanced variability of the chromosome number, and no higher level of cellular repair, limited to the two repair types described.

Cells from the peripheral blood of a patient with ‘hairy cell’ leukemia were cultivated in long-term cultures. They grew with a monolayer growth pattern and consisted of at least two cell populations. The electron microscopic morphology of the cultivated cells revealed cells resembling ‘hairy cells’ showing the typical cytoplasmic protrusions and cells with structural characteristics of plasma cells.

Soluble factors released from silica-damaged macrophages inhibit proliferation of various haematopoietic cells in long term cultures. The same holds true for damage induced by heat, non-physiological pH, freezing and thawing. This phenomenon is dose-dependent and correlates with the degree of macrophage viability. Thus, a base for measuring the amount of damage to the macrophage is established.