Cultured cells derived from male patients with Burkitt's lymphoma and harboring herpes-type virus particles were lethally irradiated. These irradiated cells induced normal peripheral leukocytes of female infants to grow within 2 to 4 weeks after mixed cultivation. Cells of a line free of this agent failed to stimulate growth. If either type of cell was cultured separately, it did not survive under the experimental conditions. Herpes-type viral antigen and C-group chromosomal marker previously described in cultured Burkitt cells were found in all of the female cell cultures that were obtained.

Cultures were initiated with peripheral leukocytes from individuals: (i) in the acute stage of infectious mononucleosis (IM); (ii) with past histories of IM; and (iii) without histories of IM and without antibodies to EB virus (EBV). In confirmation of other reports, the first group of cultures developed readily and rapidly into lines of blastoid cells. Cellular replication commenced in 24 of 25 attempts within 17 to 28 days, regardless of the technique employed; i.e., initial seeding of the leukocytes with or without addition of phytohemagglutinin onto monolayers of human diploid cells (WI-38) or direct establishment of suspension cultures. EBV was detected in all cultures by immunofluorescence and also by electron microscopy when tested. Furthermore, the nine cultures which were examined cytogenetically revealed the C-group (#10) chromosomal marker previously found in cultured Burkitt tumor cells. These findings supported the earlier conclusion that EBV is related to, if not identical with, the causative agent of IM. Cultures of the second group commenced growth only within 30 to 60 days in five of seven attempts, depending apparently upon the early presence of WI-38 cells. These cultures also revealed the presence of EBV and, in the three examined, the C-group chromosomal marker. Leukocytes of the third group, seeded onto WI-38 monolayers, failed to become established in four attempts. The possible implications of these findings are discussed.

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A healthy 30-year-old woman was discovered unexpectedly to have trisomy 18/normal chromosome mosaicism. She was ascertained because of a history of three spontaneous abortions following the birth of a healthy son. Trisomy 18 was present in 18% of her lymphocytes and 2% of her cultured skin fibroblasts. She had several minor malformations associated with trisomy 18 syndrome. She is, to our knowledge, the first person who has clinical stigmata of trisomy 18 but has normal intelligence and leads a normal family life.

Two unrelated families are presented, each with 2 affected offspring with bifid femur, absent tibia, and ectrodactyly. The healthy parents are consanguineous. It is postulated that this combination of malformations is causally heterogenous with both autosomal dominant and autosomal recessive modes of inheritance; hence, it is established as a developmental field defect.

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Although tetraploidy and tetraploid-diploid mosaicism has been well documented in studies of aborted human fetuses, no living case has been reported. This report concerns a male infant with tetraploiddiploid mosaicism who survived for 36 weeks. Because the peripheral blood cells of this infant displayed gross differences both in cell size and in DNA content, it was possible to establish that the tetraploidy observed in cultured cells was a true reflection of in vivo mosaicism.The propositus was born on December 6, 1965, after a 42-week gestation notable for a paucity of fetal movement. Birth weight was 1.7 kg, length 40.6 cm and head circumference 25.4 cm. He presented with multiple congenital anomalies. Peripheral blood smears appeared to contain two populations of neutrophilic granulocytes that differed in overall size.Immunological assessment gave the following results : 1. Serum immunoelectrophoresis performed at the ages of 4, 10 and 14 weeks showed qualitatively normal immunoglobulins. 2. Normal antibody responses were obtained to type I polio and to typhoid-paratyphoid vaccines given at age 10 weeks.3. Normal delayed hypersensitivity was obtained following stimulation with 2,4-dinitrofluorobenzene at the age of 12 weeks. There was a normal plasma growth hormone response to insulin-induced hypoglycemia at 12 weeks of age.Many of the cells in follicular centers of the spleen and lymph nodes were pale, and the lymphocytes surrounding them were bizarre, being unusually large and hyperchromatic. The histologic architecture was preserved and cortico-medullary differentiation maintained.Tetraploid-diploid mosaicism was found in ten short-term cultures of peripheral blood leukocytes obtained over a seven-month period. The average proportion of tetraploid cells was 69 % (range 64 to 77 %).Chromosomal analysis of six different primary fibroblast cultures, including that derived from the postmortem lung, were diploid in number and euploid in karyotype.Peripheral blood smears appeared to have two populations of neutrophilic granulocytes which differed from one another in their overall size. The distributions of cell diameters from all of the subject's smears showed highly significant positive skewing, in contrast to the more symmetrical distributions from the control smears.Analysis of bimodality, using a computer, indicated the presence of two normally distributed subpopulations. The,results generated are given in table IV.Cytophotometric measurements of cellular DNA content can be used to analyze tetraploid-diploid mosaicism, since tetraploid cells have twice as much DNA as diploid cells. The large cells in peripheral blood from the subject had 2.01 times the stain content of his normal appearing cells, and 1.91 times that of the control. I n order to estimate the incidence of tetraploidy among the subject's leukocytes, measurements were made on randomly selected cells a n d gave the results shown i n table V.

Using quinacrine fluorescence and Giemsa banding techniques we have identified an extra chromosome 22 in three non-mongoloid children with similar phenotypes and 47 chromosomes. In one of the children, the long arm of the extra 22 was shorter than usual. This 22q-chrcmcscme was observed in 4 normal family members with 46 chromosomes. In a fourth child, with similar physical findings, the extra G chromosome was shown to be neither a normal 21 nor 22. It must have arisen from a rearrangement in a parental gamete since it was not present in either parent's karyotype.No constellation of clinical findings, in association with an extra G chromosome, is sufficient evidence for the diagnosis of trisomy 22. The positive identification of the extra chromosome must be made using fluorescence and banding.