B Dejong

SERUM LACTATE-DEHYDROGENASE ISOENZYME-1 ACTIVITY IN PATIENTS WITH TESTICULAR GERM-CELL TUMORS CORRELATES WITH THE TOTAL NUMBER OF COPIES OF THE SHORT ARM OF CHROMOSOME-12 IN THE TUMOR

SummaryThe aim of our study was to assess the relationship between the serum lactate dehydrogenase isoenzyme 1 (S-LDH-1) activity in patients with testicular germ cell tumors and the number of copies of the short arm of chromosome 12 (12p) present in tumor. Twenty-seven adult patients with measurable tumor lesions were studied. Twenty-five had three or more copies of chromosome 12 per cell in the tumors. Nineteen had one or more copies of a specific chromosomal abnormality, an isochromosome of the short arm of chromosome 12, i(12p). Fourteen had increased S-LDH-1 levels. S-LDH-1 activity correlated significantly with the product of total tumor volume and the total number of copies of the short arm of chromosome 12 present per cell (total tumor 12p). We conclude that the total number of copies of the short arm of chromosome 12 in the tumors is most probably a factor contributing to the LDH-1 activity released from the tumors.

Pre B Cell Leukaemia in the Rat

Recently a case of spontaneous B cell leukaemia has been reported in mice (1). In rats, a transplantable lymphoid leukaemia, which arose originally in a rat undergoing chronic internal beta-irradiation of the spleen, has been described by Dibley et al. (2,3). Based on the absence of surface immunoglobulin molecules and Fcreceptors, and the presence of the Thy-1 determination the surface of the leukaeraic cells, as well as on the appearance of pyroninophilic lymphoblasts in T dependent lymphoid areas after inoculation of syngeneic recipients with tumour cells, this malignancy has been designated as a T cell leukaemia (2). We report here some of the characteristics of a pre B cell leukaemia derived from the successfully transferred in (AOxBN)F1 hybrid rats.

Ig Light Chain Gene Rearrangement and Chromosomal Abnormality in the Lama Early B-Lineage Tumour of the Rat

In the rat, few lymphoid tumours have been described so far. At the previous Germinal Centre Conference, J. Rozing and coworkers (1) reported on LAMA, a transplantable tumour that arose spontaneously in a ♂ (A0xBN)F1 rat. From this study of surface antigens and mitogen reactivity it was tentatively proposed that LAMA was a pre-B leukemia, opening up possibilities in the rat for studies of B cell differentiation events at the molecular and cellular level. On the other hand, LAMA might serve as an in vivo tumour model in the rat. Here we present data on 1) the antigenic phenotype, 2) Ig light chain gene rearrangement and 3) the karyotype of LAMA.