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Published on: March 5, 2010
Expression of CD45 isoforms in lymph node reactive hyperplasia
1Department of Pathology, University of Missouri School of Medicine, Columbia 65212.
Abstract:
The CD45 antigen family consists of multiple molecular isoforms ranging from 180 to 220 kDa. The highest Mr isoforms are recognized by monoclonal antibodies (MoAbs) designated CD45RA, while those recognizing the low Mr isoforms are designated CD45RO. T cells expressing CD45RA are "naive" or unprimed, while those expressing CD45RO have "memory." Further, stimulation of CD45RA+ T cells induces an isoform switch to the CD45RA-/CD45RO+ phenotype. The present study examined this in vitro process by determining the in vivo CD45 isoform expression of T cells from human hyperplastic lymph nodes. Hyperplastic, as opposed to nonhyperplastic, lymph nodes exhibited the expected CD45 isoform switch from CD45RA+ to CD45RO+ T cells that has been described in vitro. The percentage of CD45RO+ T cells did not correlate with other parameters of lymphoid activation. Thus, CD45RO expression probably represents a marker of differentiation and acquisition of "memory" or late cellular activation.
Insights
T cells switch from CD45RA to CD45RO isoforms upon activation, indicating differentiation. This CD45 isoform switch, observed in human hyperplastic lymph nodes, signifies memory or late T cell activation.
Area of Science:
- Immunology
- Cell Biology
Background:
- The CD45 antigen family comprises multiple molecular isoforms (180-220 kDa).
- CD45RA recognizes high molecular weight isoforms, associated with naive T cells.
- CD45RO recognizes low molecular weight isoforms, associated with memory T cells.
Purpose of the Study:
- To investigate the in vivo CD45 isoform expression in human hyperplastic lymph nodes.
- To confirm the in vitro observed T cell CD45 isoform switch in an in vivo setting.
Main Methods:
- Analysis of CD45 isoform expression (CD45RA and CD45RO) on T cells.
- Comparison of T cells from hyperplastic versus nonhyperplastic human lymph nodes.
Main Results:
- Hyperplastic lymph nodes showed an in vivo T cell CD45 isoform switch from CD45RA+ to CD45RO+.
- The percentage of CD45RO+ T cells did not correlate with other lymphoid activation parameters.
Conclusions:
- CD45RO expression in vivo likely marks T cell differentiation and acquisition of memory.
- The observed in vivo switch supports the role of CD45 isoforms as markers of T cell activation states.
