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

Area of Science:

• Immunology
• Human Genetics
• Cell Biology

Background:

• Monoclonal antibody 2B2 targets an antigen found on human peripheral blood leukocytes but not on most proliferating cells.
• This antigen comprises two surface-labeled membrane glycopolypeptides of 86,000 and 145,000 molecular weights.
• The antibody exhibits strong mitogenic effects on normal human lymphocytes.

Purpose of the Study:

• To characterize the antigen recognized by monoclonal antibody 2B2.
• To determine the cellular localization and function of the antigen.
• To assign the genes encoding these membrane glycoproteins to a specific human chromosome.

Main Methods:

• Utilizing a mouse monoclonal antibody (2B2) to identify and isolate cell surface antigens.
• Employing surface labeling and immunoprecipitation to determine the molecular weight of the recognized glycopolypeptides.
• Generating and analyzing mouse-human T-lymphocyte somatic cell hybrids to map gene locations.
• Correlating antigen expression with the presence of specific human chromosomes in hybrid clones.

Main Results:

• The antibody 2B2 precipitated two distinct surface-labeled membrane glycopolypeptides (86,000 and 145,000 MW).
• The antigen is present on most human peripheral blood leukocytes but absent from most proliferating cells.
• Somatic cell hybrid analysis successfully assigned the genes for these glycoproteins to human chromosome 21.
• Antigen expression correlated with the presence of chromosome 21 in the hybrid cell lines.

Conclusions:

• Monoclonal antibody 2B2 recognizes a specific leukocyte antigen involved in lymphocyte activation.
• The genes encoding the 86,000 and 145,000 MW membrane glycoproteins are located on human chromosome 21.
• This finding provides a genetic marker for chromosome 21 and contributes to understanding leukocyte differentiation and proliferation.