Measurement of cytokine release by human cells. A quantitative analysis at the single cell level using the reverse haemolytic plaque assay.

The reverse haemolytic plaque assay has been adapted to detect and measure the release of such cytokines as interleukin-1, -2 and -6, GM colony-stimulating factor or interferon-gamma by individual human cells derived from either peripheral blood or enzymatically dispersed breast carcinomas. Since each of these peptides is released by more than one cell type, this in vitro assay has been coupled with immunocytochemistry to identify the particular cell type(s) contributing to the release of each cytokine. This technique is useful in (i) obviating the need for purification of a given cell type prior to estimating cytokine release, and (ii) evaluating quantitative differences in secretion amongst cells of a particular type. Such a method has the additional advantage over most alternative methods applied at the single cell level in that the cells remain viable at the end of the assay and can be used in further studies. This assay thus provides a powerful new tool in the investigation of the role of cytokines in both the normal modulation of the immune system and the development of such diseases as neoplasia.