Human cell surface antigens coded by genes on chromosome 21

Assignment of gene(s) coding for antigen defined by monoclonal antibody 2B2

A mouse monoclonal antibody (2B2) recognizes an antigen which is present on most human peripheral blood leukocytes but is absent from most proliferating cells. The antibody precipitated two surface-labeled membrane glycopolypeptides with molecular weights of 86,000 and 145,000, and it was strongly mitogenic to normal human lymphocytes. Somatic cell hybrids have been used for assigning the genes coding for these membrane glycoproteins to human chromosome 21. The assignment was based on correlation of antigen expression on mouse-human T-lymphocyte hybrids with the presence of human chromosomes in the same hybrid clones.

Assignment of gene coding for cell surface glycoprotein with a molecular weight of 75,000 to human chromosome 11

The gene for a cell surface glycoprotein recognized by a mouse monoclonal antibody (Mab 4), has been assigned to human chromosome 11 by the study of mouse-human lymphocyte hybrids. The antigen is present on all human peripheral blood leukocytes, on human fibroblasts, and on human lymphoid and erythroid cell lines, but not on erythrocytes. Immunoprecipitation and polyacrylamide slab gel electrophoresis of both human cells and mouse-human hybrid clones carrying human chromosome 11 show that the apparent molecular weight of this glycoprotein is 75,000.

Somatic cell genetic approaches to Down's syndrome

Somatic cell genetic analysis of mutants of Chinese hamster ovary cells with deficient purine synthesis and of hybrids between these mutants and human cells is described. Data are presented substantiating that two genes for enzymes of purine synthesis, AdeC and AdeG, can be coordinately regulated in mammalian cells. Analysis of a human-hamster hybrid cell, Ade C/21, which contains a normal complement of hamster chromosomes and human chromosome 21 as its only human genetic component recognizable by electrophoretic and immunogenetic techniques demonstrates that genes associated with the presence of human chromosome 21 and required for the synthesis of specific polypeptides and specific human lethal cell surface antigens can be detected in these hybrids.