Immunophenotypic attributes of benign peripheral blood gammadelta T cells and conditions associated with their increase.
BACKGROUND
In comparison to alphabeta T cells, little is known about the immunophenotype of healthy peripheral blood gammadelta T cells or about conditions associated with expansion of this usually minor T-cell subset.


OBJECTIVE
To study the immunophenotype of increased nonneoplastic peripheral blood gammadelta T cells and to determine clinical conditions associated with this laboratory finding.


METHODS
Flow cytometric T-cell phenotyping studies performed on 352 consecutive peripheral blood specimens were reviewed, and 62 cases (18%) in which gammadelta T cells comprised either more than 5% of the total lymphocytes or had an absolute count of more than 200 cells per muL or both, were studied further. Clinical data were available from 36 cases.


RESULTS
The gammadelta T cells often had an immunophenotype distinct from the alphabeta T cells, with differences in CD5 expression as the most common (n = 17), followed by differences in CD3 (n = 6) and CD7 (n = 3). CD16 coexpression by the gammadelta T cells was also frequent (n = 20). In 28 (78%) of 36 cases, there were one or more associated conditions: infection/inflammatory disease (n = 18), autoimmune disease (n = 9), lymphoproliferative disorder (n = 6), and splenectomy (n = 3).


CONCLUSIONS
Circulating gammadelta T cells are immunophenotypically distinct from alphabeta T cells, and mild increases in these cells are not uncommon and may be associated with immune system activation and splenectomy. Recognition of this phenomenon is important because reactive gammadelta T cells can exhibit distinctive immunophenotypic features that are also encountered in neoplastic conditions, such as T-cell large granular lymphocytic leukemia.
Roden
Anja C
AC
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN55905, USA. roden.anja@mayo.edu
Morice
William G
WG
Hanson
Curtis A
CA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002452:Cell Count; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D054066:Leukemia, Large Granular Lymphocytic / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D012189:Retrospective Studies; D013156:Splenectomy; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*
D016692:Receptors, Antigen, T-Cell, gamma-delta