IgE‐induced histamine release from rat basophilic leukemia cell lines: isolation of releasing and nonreleasing clones

The rat basophilic leukemia (RBL) cell lines were cloned and the various sublines compared for their chromosome number, IgE‐mediated histamine release and for IgE surface receptors. It was found that cell lines started from tumors at different times vary in both their chromosome number and their ability to release histamine by an IgE‐mediated reaction. RBL‐I and III have ∼ 44 chromosomes and did not respond to an IgE‐mediated reaction, whereas RBL‐II and RBL‐IV have 68–73 chromosomes and showed moderate levels of histamine release (percent release x̄ = 5 ± 2 and 10 ± 4, respectively). The cloning of the RBL‐IV line resulted in some sublines which were excellent histamine releasers (range 39–100%) and some which were relatively refractory (< 10%) to IgE‐mediated histamine release. These clones did not differ significantly in chromosome number. Recloning the releasing lines gave rise to poor releasers, whereas the recloning of poor releasers did not produce good releasers indicating that the mutational drift in culture is toward loss of histamine‐releasing capacity. The number of IgE receptors and the rate of IgE association and dissociation were similar for the different cell lines. The study failed to disclose significant molecular weight differences in the IgE receptor from the various clones and sublines indicating that the failure to release probably does not reside in the receptor. The various cloned sublines are phenotypically stable, and the isolation of excellent histamine‐releasing sublines are useful for studies of the complex phenomenon of histamine release.