Blood, 15 April 2001, Vol. 97, No. 8, pp. 2528-2529
CORRESPONDENCE
To the editor:
Expression of CD10 by human T cells that undergo apoptosis both
in vitro and in vivo
We are glad to hear that Drs Bladon and Taylor1
confirmed our data that CD10 can be found on the surface of T cells
induced into apoptosis, although they used a somewhat different system. As for the differences reported by Drs Bladon and Taylor, we wish to
point out that there are several variables to be taken into account.
First, the anti-CD10 mAb employed may greatly influence the results
obtained, and the definition of "weak" or "strong" staining
varies depending upon the CD10 mAb used. In addition, we believe that
staining cannot be defined as percentage of weakly or strongly stained
cells because we have better methods of determining immunofluorescence
intensity, such as flow-cytometry profiles, as we
reported.2 With flow cytometry analyses of peripheral blood from HIV-seropositive individuals, it is possible to
segregate populations of CD10+/CD3+ T
cells with various degrees of CD10 positivity that probably represent
cells as different stages of the apoptotic process. These
CD10+ T cells are not necrotic, as demonstrated by
triple-staining tests capable of detecting necrotic cells.
Perhaps in connection with this, we should mention some of our recent
data that show down-regulation of CD10 by necrotic cells.
Second, the methods used to induce apoptosis both in vivo or in vitro
may influence the mode and quantity of CD10 expression. This
possibility may partly explain some of the differences between the
Bladon and Taylor's data and ours. We have evidence in favor of this
hypothesis in preliminary studies in which T cells have been induced
into apoptosis by different signals or by the same signal with
different intensity (ie, different concentrations of CD95 mAb).
We believe that CD10 may have a role in apoptosis, as suggested by the
finding that there is considerable CD10 synthesis upon the induction of
apoptosis. But it is difficult to accept that the only role of
molecules newly synthesized during apoptosis is that of facilitating
the clearance of apoptotic cells from circulation. Apoptosis of T (and
also B) cells primarily takes place in the peripheral lymphoid organs.
The environment is likely to participate in the regulation of
apoptosis. Therefore, it is possible that the newly synthesized
molecules may play a role in this regulatory process. These
considerations may open up new avenues of research on T-cell physiology
besides offering the opportunity of discovering new markers which
facilitate the in vivo identifications of apoptotic T cells.
Giovanna Cutrona and Manlio Ferrarini
Servizio di Immunologia Clinica Istituto Nazionale per la
Ricerca sul Cancro Genoa, Italy
References
1.
Bladon J, Taylor P.
The expression of CD10 by apoptotic lymphocytes is preceded by a pronounced externalization of phosphatidylserine [letter].
Blood
2000;96:4009[Free Full Text].
2.
Cutrona G, Leanza N, Ulivi M, et al.
Expression of CD10 by human T cells that undergo apoptosis both in vitro and in vivo.
Blood.
1999;94:3067-3076[Abstract/Free Full Text].
