Northern blot and RT-PCR analysis of MHC-I and MICA expression in myeloma cell lines. (A) Northern blot analysis. Total RNA (10 μg) from T2 (lane 1), KMS21BM (lane 2), KMS12BM (lane 3), KMS12PE (lane 4), KMS26PE (lane 5), KMS11PE (lane 6), and HeLa (lane 7) cell lines was hybridized with MHC-I and MICA cDNA fragments. For the evaluation of gel load and transfer, the same filters were rehybridized with a fragment of GAPDH cDNA. Reciprocal amounts of MHC class I heavy chains and MICA transcripts levels were observed between BM and PE myeloma cell lines. (B) RT-PCR was performed from RNA preparations in duplicate, using specific primers for MHC class I, and MICA (40 cycles). cDNAs were obtained from: KMS12BM (lanes 1-2), KMS12PE (lanes 3-4), KMS21BM (lanes 5-6), and KMS21PE (lanes 7-8). The products were analyzed by agarose gel and were normalized using the levels of GAPDH (20 cycles) as an internal control. The RT-PCR analysis confirmed the inverse correlation between the MHC class I and MICA transcript levels found in BM and PE cell lines.