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Expression of CD4 by human megakaryocytes
R S Basch1, Y H Kouri, S Karpatkin
1Department of Pathology, Kaplan Cancer Center, New York University Medical School, NY 10016.
Summary
Human megakaryocytes, the cells that produce platelets, express the CD4 antigen. This finding suggests a potential pathway for human immunodeficiency virus type 1 (HIV-1) to infect these critical cells.
Area of Science:
- Immunology
- Hematology
- Virology
Background:
- The CD4 antigen is the primary receptor for human immunodeficiency virus type 1 (HIV-1) on T cells.
- Impaired thrombopoiesis in HIV-1-related thrombocytopenia suggests potential megakaryocyte infection.
- A receptor for HIV-1 entry on megakaryocytes was investigated.
Purpose of the Study:
- To determine if human megakaryocytes express the CD4 receptor.
- To investigate the potential for HIV-1 entry into megakaryocytes.
Main Methods:
- Analysis of bone marrow specimens from normal, uninfected subjects.
- Three-color flow cytometry using monoclonal antibodies against CD4 and CD41 (a megakaryocyte/platelet glycoprotein).
- Direct microscopic examination with two-color immunofluorescence and phase-contrast microscopy.
Main Results:
- Approximately 0.4% of nucleated bone marrow cells were identified as megakaryocytes.
- 20-26% of identified megakaryocytes expressed the CD4 antigen.
- Platelets did not express CD4.
Conclusions:
- Human megakaryocytes express CD4 on their surface.
- This expression suggests megakaryocytes may be susceptible to HIV-1 infection.
- CD4 on megakaryocytes could serve as a portal of entry for HIV-1.