BCR/ABL p210, p190 and p230 fusion genes in 250 Mexican patients with chronic myeloid leukaemia (CML).

There are two major forms of the BCR/ABL fusion gene, involving ABL exon 2, but including different exons of BCR gene. The transcripts b2a2 or b3a2 code for a p210 protein. Another fusion gene leads to the expression of an e1a2 transcript, which codes for a p190 protein. Another, less common fusion gene is c3a2[e19a2], which encodes a p230 protein. The incidence of one or the other rearrangement in chronic myeloid leukaemia (CML) patients varies in different reported series. This study was designed to determine the frequency of coexpresion of the p210, p190 and p230 transcripts in 250 Mexican patients with CML. We performed nested and multiplex reverse transcriptase polymerase chain reaction (RT-PCR) on bone marrow samples from adult patients and found that all cases were positive for some type of BCR/ABL rearrangement. In 226 (90.4%) patients it was p210, while the remaining 9.6% showed coexpression or one of the transcripts of p190/p210/p230. In 7% of patients with p210 expression there are both isoforms (b3a2/b2a2), presumably the result of alternative splicing. The rate of coexpression of the p190/p210 transcripts was 5%, which is much lower than in other reports. This may be due to the technical factors. These patients had high platelet counts, marked splenomegaly and chromosomal abnormalities in addition to Ph'. Other types of coexpression seen were p210/p230 and p190/p210/p230, in patients with high-risk clinical factors. Our study confirms the occurrence of coexpression of different BCR/ABL transcripts, although the rate (9.6%) was much lower than has been reported in other populations. This may reflect either the sensitivity of the detection techniques used or the possibility of genetic differences between the populations studied. Coexpression may be due to alternative splicing or to phenotypic variation, with clinical courses different from classical CML.

The presence of anti-leukoblast antibodies as complement fixation agents in leukemia patients imm-nized with leukoblats treated with neuraminidase and radiation.

Six adult patients with acute myeloblastic leukemia were treated with chemotherapy and immunotherapy. This was done with cultured autologous leukoblasts, treated with neuraminidase of Vibrio cholerae and radiation, and injected six to ten times each eight to ten days between the chemotherapy cycles. Class IgC leukemic anti-leukoblast antibodies which are able to activate the C3 component of the complement system were found in the serum of patients. Five patients have been in complete remission for more than twenty months and the sixth patient for ten months. Antibodies for C3 fixation were not found in the serum of five other patients who were not immunized, nor in five healthy control subjects.