Reet Tees

Clones of Killer and Helper T Cells: Growth Requirements, Specificity and Retention of Function in Long-Term Culture

Lymphocyte reactions are complex, involving interactions between lymphocyte subsets and other accessory cells. An overall outline of these interactions has emerged from studies of unseparated or partially separated cells from lymphoid organs in culture. However, progression from mapping of events at a population level to an understanding of mechanisms at the level of single cells and of molecules demands the availability of populations which are homogeneous to a degree not achievable by present methods of cell separation. Continuously growing clones of lymphocytes, capable of unlimited expansion in culture while maintaining normal function and responsiveness to regulation, would represent ideal tools for dissection of these mechanisms. Until very recently, such lines were not available. While lymphocytes could be induced to proliferate in culture, their response was limited to a few days, insufficient to provide clonal populations of the required size. The essential breakthrough for T lymphocytes was achieved 3 years ago, when Morgan and coworkers (1976) and Ruscetti et al. (1977) showed that the proliferation of human T cells could be extended for periods of many months if the cells were supplied with medium conditioned by lectinor alloantigen-stimulated peripheral blood cells. The activity of these conditioned media was subsequently attributed to a protein regulator known now as T cell growth factor (TCGF) or Interleukin 2 (IL-2). Growing T cells are now understood to depend on TCGF absolutely for both

A Cocktail of Three Monoclonal Antibodies Significantly Increases the Sensitivity of an Enzyme Immunoassay for Human Granulocyte-Macrophage Colony-Stimulating Factor

A sensitive and specific two-site ELISA was developed for human granulocyte-macrophage colony-stimulating factor (huGM-CSF) based on monoclonal antibodies (mAbs) which have been selected for high affinities and different epitope specificities. Using a cocktail of three mAbs, both for coating and, in their labeled form, for detection, a major increase in sensitivity was achieved (20-fold) compared to a two-site assay employing two different mAbs (one for coating and one for detection). The assay is as sensitive as the most sensitive biological assays. Recombinant mammalian cell expressed and natural huGM-CSF can be reliably detected down to 100 pg/ml (7 pmol/l). In contrast to conventional bioassays, the ELISA is highly specific for huGM-CSF and does not detect other human lymphokines. Results from quantification of recombinant and natural huGM-CSF in ELISA and bioassay correlate.

Skim Passage: A Rapid Method of Adapting Influenza Viruses to New Host Tissues

Skim passage is a series of single-growth cycles whose earliest yield is separated and used, without dilution, for further passages. The method allows effective selection of fast-growing mutants, and the time of adaptation can be shortened to a few days instead of the several weeks or months taken by the conventional sequence of blind passages. The technical details are illustrated by three examples, which also serve to display the scope and limitations of the method.