Cloning non-transformed sheep B cells.

The capacity to clone B cells and establish permanent B cell lines has greatly facilitated a wide variety of studies characterising the growth, differentiation, and gene expression of murine and human B cells. Similar investigations of B cell biology for other species have been severely restricted by an inability to culture or clone B cells. This is the first report of a method to clone non-transformed sheep B cells using a culture system based on murine CD154 and a combination of human gamma chain-common cytokines. Sheep Peyer's patch B cells were cultured for 120 days and then cloned by limiting dilution culture. The parental B cell culture contained both surface immunoglobulin (sIg)M(+) and sIgG1(+) B cells and both types of B cell were cloned. Clonality was confirmed by PCR analysis of Ig heavy chain (HC) and light chain (LC) expression and DNA sequencing of HC V genes. There was agreement between the PCR and flow cytometric analyses of HC isotype expression on the B cell clones but the available monoclonal antibodies specific for sheep lambda and kappa LC did not react with all clones. Soluble Ig was detected in the culture supernatant of sIgG1(+) clones but not sIgM(+) clones. The B cell clones remained dependent upon CD154 and gamma chain-common cytokine co-stimulation for sustained growth and maintained stable Ig expression. The cloning of non-transformed sheep B cells should provide a valuable tool for studying sheep B cell biology, establishing Ig HC- and LC-specific monoclonal antibodies, analysing the B cell Ig repertoire, and may be used to produce sheep monoclonal antibodies.