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Alveolar lymphocytes express high levels of CD69, according to one paper even in normal
subjects, but definitely where there is an alveolitis (Soluble and cellular markers of T cell
activation in patients with pulmonary sarcoidosis. Am Rev Respir Dis 1993 Sep;148(3):643-9
Hol BE etal ) This is consistent with their presence at a mucosal site of antigen exposure.
Research by Holt and colleagues suggests that the alveolar environment, in particular the
presence of alveolar macrophages, permits activation but specifically keeps the lid on
proliferation of alveolar T-cells, as excessive proliferation would affect the gas exchange
mechanism. Obviously if sufficient activation takes place, such antiproliferative machanisms
can be overcome, leading to recruitment of monocytes and appropriate t cell responses
(Huffnagle et al, J Immunol).
Now if the patient you are investigating has (perhaps) a problem with initial T cell activation
then normal proliferative responses may not ensue in pulmonary defence and the defect may
predispose to pulmonary infections. Have you looked at later activation markers eg CD25 or
HLA-DR expression? It would be very interesting to look at BAL Tcells and their CD69
expression but on the other hand perhaps a BAL would be risky in her setting. You din't say
what kind of pulmonary infections she is getting: are they specifically associated with defective
Tcell immunity?
Dr. D O Donnell,
Lung Fibrosis Unit,
University College Dublin,
Ireland
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CD-ROM Vol 3 was produced by Monica M. Shively and other staff at the
Purdue University Cytometry Laboratories and distributed free of charge
as an educational service to the cytometry community.
If you have any comments please direct them to
Dr. J. Paul Robinson, Professor & Director,
PUCL, Purdue University, West Lafayette, IN 47907.
Phone: (765)-494-0757;
FAX(765) 494-0517;
Web