In vivo transfer of persisting (P) cells; further evidence for their identity with T-dependent mast cells.

Previously we described the persistent in vitro growth of lines of cells (persisting [P] cells) that shared many cytochemical, biochemical, and functional characteristics with mast cells and depended for their survival and growth on a specific T cell-derived factor, P cell-stimulating factor (PSF). Here we present further evidence for their identity with the T-dependent or atypical subset of mast cells and show that they retain characteristics of T-dependent mast cells when transferred in vivo. One week after the injection of P cells into the dermis of mutant Wf/Wf mice, which have a genetically determined deficiency in mast cells, large numbers of mast cells were present at the injection site, although by 2 wk or later these had disappeared. These mast cells resembled T-dependent mast cells rather than connective tissue mast cells in terms of their size and staining characteristics. Further evidence that these mast cells belonged to the T-dependent subset was that they retained their sensitivity to PSF. Thus, if P cells were injected into the dermis of Wf/Wf mice that bore in one groin a subcutaneous tumor (WEHI-3B) that produced PSF, increased numbers of mast cells were still evident at the injection site 4 wk later; this was not the case in mice bearing a non-PSF-producing variant of the same tumor. Experiments with cloned P cells generated from mice bearing the beige (bgJ/bgJ) mutation and with the giant granules of cells of this genotype used as a marker showed conclusively that the mast cells at the injection sites were derived from the injected P cells. P cells sensitized in vitro with monoclonal antigen-specific IgE or IgG1 antibodies and then injected intracutaneously into W/Wv mice transferred local cutaneous anaphylactic responses. P cells sensitized with IgG1 transferred local cutaneous anaphylactic responses to rats. These results support the view that P cell lines are cognate with the atypical or T-dependent subset of mast cells and that these cells retain their functional capabilities when injected in vivo.