Characterization of Cell Phenotype by a Novel cDNA Library Subtraction System: Expression of CDSa in a Mast Cell-Derived Interleukin-4-Dependent Cell Line

We have established a unique variant cell line, MC/9.IL-4, which continuously proliferates in the presence of interleukin-4 (IL-4). from a murine interleukin-3 (IL-3)-dependent mast cell line, MC/9 (referred t o as MC/9.IL-3). Compared with MC/9.IL-3 cells, MC/9.IL-4 cells are smaller, lack cytoplasmic granules and metachromasia, carry a very small amount of histamine, and express fewer high-affinity IgE receptors (IgERs) and IL-3 receptors. To further characterize MC/9.IL-4, we developed a novel method to enrich cell typespecific cDNAs by cDNA library subtraction and applied it for MC/9.IL-3 versus MC19.IL-4. Sequence analysis of cDNA clones isolated by this technique showed that MC/9.IL-4 cells specifically express CD& and expression of mast cellspecific proteases and major histocompatibility complex class II (MHCII) is considerably decreased. It was also noted