Correspondence

Platelet Satellitism

N Engl J Med 1998; 339:131-132July 9, 1998

Article

To the Editor:

With respect to the image of platelet satellitism presented by Drs. Shahab and Evans (Feb. 26 issue)1: complexes of platelets and polymorphonuclear neutrophils are not solely an in vitro phenomenon seen in blood treated with EDTA as an anticoagulant. Complexes of platelets and polymorphonuclear neutrophils can be observed in whole blood treated with citrate and heparin as anticoagulants.2 Similar observations have been made in a variety of separated cell systems under static and dynamic conditions.3 These complexes are principally dependent on the platelet alpha-granule glycoprotein CD62P (P-selectin), which is rapidly expressed on the platelet surface after exposure to a stimulus to activation. The platelet fibrinogen receptor glycoprotein IIb/IIIa and the neutrophil β₂ integrin CD11b/CD18 are also involved in the formation of polymorphonuclear neutrophils.3 In contrast to the rosettes observed by Drs. Shahab and Evans, polymorphonuclear neutrophils are dependent on divalent cations and are abolished by anticoagulation with EDTA. Polymorphonuclear neutrophils have been observed in a number of patient populations and may reflect the extent of platelet activation in vivo.4 Polymorphonuclear neutrophils consist of activated subpopulations of both cell types, with complexes of neutrophils having greater expression of β₂ integrins than cells that are not in complexes.2 In view of recent work describing how immobilized platelets can support multistep inflammatory-cell adhesion and transmigration in a manner similar to that of the vascular endothelium,5 polymorphonuclear neutrophils may be of considerable physiologic importance.

Although artifactual platelet rosetting can occur and may be a cause of spurious thrombocytopenia, the presence of polymorphonuclear neutrophils may also lead to a decrease in free platelets in vivo, and this will not be detected by standard methods of platelet enumeration. Platelet–leukocyte interactions are important in modulating inflammation and hemostasis and should not be confused with the image presented by Drs. Shahab and Evans.

Mark Peters, M.B., Ch.B., M.R.C.P.
Robert S. Heyderman, M.R.C.P., Ph.D.
Nigel J. Klein, M.R.C.P., Ph.D.
Institute of Child Health, London WC1N 1EH, United Kingdom

5 References

1. 1

   Shahab N, Evans ML. Platelet satellitism. N Engl J Med 1998;338:591-591
   Full Text | Web of Science | Medline

2. 2

   Peters MJ, Heyderman RS, Hatch DJ, Klein NJ. Investigation of platelet-neutrophil interactions in whole blood by flow cytometry. J Immunol Methods 1997;209:125-135
   CrossRef | Web of Science | Medline

3. 3

   Evangelista V, Manarini S, Rotondo S, et al. Platelet/polymorphonuclear leukocyte interaction in dynamic conditions: evidence of adhesion cascade and cross talk between P-selectin and the beta 2 integrin CD11b/CD18. Blood 1996;88:4183-4194
   Web of Science | Medline

4. 4

   Gawaz M, Dickfeld T, Bogner C, Fateh-Moghadam S, Neumann FJ. Platelet function in septic multiple organ dysfunction syndrome. Intensive Care Med 1997;23:379-385
   CrossRef | Web of Science | Medline

5. 5

   Diacovo TG, Roth SJ, Buccola JM, Bainton DF, Springer TA. Neutrophil rolling, arrest, and transmigration across activated, surface-adherent platelets via sequential action of P-selectin and the beta 2-integrin CD11b/CD18. Blood 1996;88:146-157
   Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: We agree with the comment of Peters et al. regarding platelet–neutrophil interactions in vivo and their importance in modulating inflammation and hemostasis. However, platelet satellitism as we described it is a different phenomenon. It is observed solely after blood treated with an anticoagulant is incubated at room temperature.1 It is not reproduced if blood is incubated at body temperature or smears are made immediately from either blood treated with EDTA as an anticoagulant or capillary blood.1,2 We agree with Peters et al. that under similar conditions, both heparin-treated blood and citrated blood have occasionally been observed to produce the same phenomenon.1 However, others have not observed this effect with anticoagulants other than EDTA.2

The underlying mechanism of platelet satellitism is not fully understood. IgG autoantibodies have been implicated,3 and more recent studies have indicated that these autoantibodies are directed against the glycoprotein IIb/IIIa complex of the platelet membrane and the neutrophil Fcγ receptor III (CD16).4 It was postulated that at low temperatures, the chelation of calcium ions by EDTA alters the conformation of the glycoprotein IIb/IIIa complex of platelets and the Fcγ receptor III of neutrophils. This change may unmask epitopes for the IgG autoantibody, which forms a bridge between platelets and neutrophils, and hence, reveal the hematologic picture.4 An alternative, nonimmunologic mechanism has been proposed by Christopoulos and Mattock, who suggested that thrombospondin or some other alpha-granule platelet protein had a role after they observed that adherence to neutrophils involved only platelets that stained strongly for thrombospondin.5

Nasir Shahab, M.D.
Maria L. Evans, M.D.
University Hospitals and Clinics, Columbia, MO 65203

5 References

1. 1

   Field EJ, MacLeod I. Platelet adherence to polymorphs. BMJ 1963;2:388-389
   CrossRef

2. 2

   Bizzaro N. Platelet satellitosis to polymorphonuclears: cytochemical, immunological, and ultrastructural characterization of eight cases. Am J Hematol 1991;36:235-242
   CrossRef | Web of Science | Medline

3. 3

   Zeigler Z. In vitro granulocyte-platelet rosette formation mediated by an IgG immunoglobulin. Haemostasis 1974;3:282-287
   Medline

4. 4

   Bizzaro N, Goldschmeding R, von dem Borne AE. Platelet satellitism is Fc γ RIII (CD16) receptor-mediated. Am J Clin Pathol 1995;103:740-744
   Web of Science | Medline

5. 5

   Christopoulos C, Mattock C. Platelet satellitism and α granule proteins. J Clin Pathol 1991;44:788-789
   CrossRef | Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   Alejandro Lazo-Langner, Josefa Piedras, Penlope Romero-Lagarza, Carmen Lome-Maldonado, Jorge Snchez-Guerrero, Xavier Lpez-Karpovitch. (2002) Platelet satellitism, spurious neutropenia, and cutaneous vasculitis: Casual or causal association?. American Journal of Hematology 70:3, 246-249
   CrossRef