Previously we have reported that rodent mast cells synthesize the mRNA encoding the u and f 3 integrin chains (u4, 61 and (37) of the lymphocyte Peyer's patch adhesion molecule (LPAM)-1 and LPAM-2 lymphocyte homing receptors, and that they possess an a4-containing integrin complex on their cell surface. In this report, we have examined the expression of these integrin chain genes by mature connective tissue mast cells (CTMC) and by bone marrow-derived mast cells (BMMC) differentiated from bone marrow precursor cells in the presence of interleukin (IL)-3 and/or the c-kit ligand (also known as mast cell growth factor and stem cell growth factor). High levels of both the f37 and transcripts were present in mature CTMC while those encoding the u4 chain were absent. Similarly, when BMMC were grown in IL-3 for 28 days and analyzed for integrin chain transcripts, those specific for the u4 chain were also diminished compared to p7 and transcripts. To compare the expression of these integrin genes during mucosal mast cell and CTMC development, BMMC were derived in the presence of IL-3 alone, c-kit alone, or IL-3k-kit together.These experiments indicated that c-kit inhibited the transcription of the p7 and FceRI genes while enhancing UJ transcript levels. The enhancement of u4 levels, however, was abrogated with the addition of IL-3. Similarly, the c-kit-induced depression of p7 and FCE RI transcript levels was overcome by the addition of IL-3.These data suggest that the integrin complexes synthesized by the mast cells may differ depending upon their path of differentiation and that another u chain integrin may be synthesized to complex with the f 17 andlor chains.