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Posted by on May 24, 2013 in Explain To Me |

Explain To Me: CD Numbers (Clusters of Differentiation)

Explain To Me: CD Numbers (Clusters of Differentiation)

This post is still under construction.

Disregard its content, if any, as it only contains raw reference material for the future post.

Do you have any questions about CD Numbers? Then please head for the “Why Is It All So Confusing?” forum and we'll try and help.

Watch this 25sec.  video to get a gist as to CD numbers.




As you know, B cells differentiate into cells with multiple and different roles/tasks when it comes to cellular immunity.

MAB’s target the clusters of differentiation (CD) on plasma cells. These clusters show up as brightly colored multi-colored regions in different areas of a graph. (slide 7) Where they ‘cluster’ is how they are differentiated, thus the name CD.

How the cells ‘cluster’ into differ groups tells us what surface molecules (antigens) they have on their surface. There are 250 CD surface molecules. When the cell lights up in a cluster it is called CD positive and when it doesn’t it is called CD negative. The number tells us what they numerically designated that cluster as out of 250.

Think of a cell as a pin cushion and the antigens on the surface as multi-colored pinheads, you might recall in your mom’s/grandmom’s pin cushions.

The clusters tell us the immunophenotype (pin head colors) of the plasma & myeloma cells

CD’s are different for normal plasma cells(PC) vs neoplastic PC and the process of differentiating clusters is called immunophenotyping.

Normal PCs express: CD19+, CD20–, CD45+, and CD56–.

Myeloma cells are typically CD56, CD38, CD138 positive and CD19 and CD45 negative. CD138 has also been shown to be an adhesion molecule myeloma cells use to bind to bone stroma and lytic lesions in MM often express CD19.

Therapeutic antibodies (MAB) can directly induce apoptosis or growth arrest when they bind to the cell surface antigen (CD) on the myeloma cell.