T200 alternate exon use in murine lymphoid cells determined by reverse transcription-polymerase chain reaction.

T200 glycoproteins of lymphoid and myeloid cells exhibit cell lineage-specific structural heterogeneity. Peptide heterogeneity appears to arise from alternate 5'-exon use (Ex-4, 5, and 6), potentially giving rise to eight distinct forms of T200 mRNA containing 0 to 3 of these alternate exons. A method is described for determining the number and identity of the three alternate T200 exons expressed in cells by using the polymerase chain reaction (PCR) and the reverse transcription-polymerase chain reaction (RT-PCR) without prior purification of RNA. Synthetic primers flanking the alternate exon region of T200 were designed to yield products for each possible exon combination having unique size and restriction enzyme sites. PCR amplification of plasmids containing T200 cDNA with none (pLy-5-68) or all three (p70Z/3-3) known alternate exons resulted in the amplification of 186 and 603 bp products, respectively. That amplified products were derived from T200 cDNA was verified by restriction enzyme mapping of each PCR product. T200 cDNA prepared from cell lines utilizing no alternate exons (BW5147) or all three exons (70Z/3.12) were analyzed by RT-PCR and contained amplified products of 186 bp (zero alternate exons) and 603 bp (containing Ex-4+5+6), respectively. RT-PCR of EL4 cells revealed approximately 186 and 330 bp products suggestive of zero and one alternate exon forms. Restriction mapping confirmed that EL4 cells contained a zero-exon form and a one-exon form containing Ex-5. Analysis of the 3B3 pre-B cell line yielded 186, 330, 460, and 603 bp products; restriction mapping revealed T200 mRNA for a zero alternate exon form, two distinct one- and two-exon forms (Ex-4; Ex-5; Ex-4+5; Ex-5+6), and a three-exon form (Ex-4+5+6). Other lymphoid cell lines were heterogeneous in T200 alternate exon use, with distinct patterns distinguishing B and T cells. RT-PCR can facilitate the analysis of variations in T200 alternate exon use among developmentally and functionally distinct lymphoid and myeloid cells.