Human lymphocyte culture and chromosome analysis.

INTRODUCTIONPhytohaemagglutinin (PHA), a lectin derived from the red kidney bean, is a powerful mitogen for human T-cells. When PHA is added in vitro to whole blood, mitotic cells can be found after 48 h, with a peak mitotic index at ~64-72 h. The convenience of peripheral blood as a source of human cells, the abundance of mitotic cells, and the simplicity of the cell culture technique make this the most convenient approach to study human chromosomes for both clinical and research purposes. This method of chromosome preparation provides metaphase cells that can be stained by a variety of methods or used for fluorescence in situ hybridization (FISH). The most common chromosome staining techniques involve exposing fixed preparations to a protease (e.g., trypsin), followed by an appropriate semipermanent stain. The characteristic banding patterns obtained reflect both structural and functional differences in different parts of the chromosomes. The staining procedure described here provides a Giemsa banding pattern using trypsin with Wright stain (i.e., GTW banding). This procedure is reliable and, with only minor modifications, suitable for preparing chromosomes from a variety of human tissues.