[IGM hyperimmunoglobulinemia anti-phosphatidylethanolamine antibodies of the IgM isotype: clinical and biological study of 72 patients with immune disorders].
OBJECTIVE
Antiphosphatidylethanolamine antibodies (aPE) are zwitterionic antiphospholipid antibodies that have been recently described in antiphospholipid syndrome. IgM is the most frequently observed isotype. We assessed the potential relationship between serum IgM levels and their presence.


METHODS
Seventy-two patients (66 females, 6 males) positive for aPE of the IgM isotype were followed up for 2 years. They suffered from either an autoimmune disease or had clinical signs suggesting the existence of antiphospholipid syndrome or other immune disorders. Seventy-two control patients (58 females, 14 males) of similar age, with other immune disorders were also included in the study. For each of them, the IgM level was obtained and hyper-immunoglobulinemia M (hyper-IgM) was defined as a value upper than 2.5 g/L. Search for aPE of the IgM isotype was made using an in-house Elisa test.


RESULTS
Half of the aPE-positive patients had serum hyper-IgM, whereas none of the aPE-negative patients had hyper-IgM. All IgMs were polyclonal. There was a positive correlation (r = 0.57, P = 0.001) between the level of IgM and the optical densities obtained by Elisa. The presence of a hyper-IgM did not modify the clinical manifestations (arterial and venous thromboses, recurrent fetal losses), nor the positivity of lupus anticoagulant, anticardiolipin and anti-beta-2-glycoprotein 1 antibodies.


CONCLUSIONS
The positive correlation between the IgM level and aPE level is of value, as it suggests a possible relationship between lymphocytic activation and auto-antibodies production, which does not concern only aPE. Further studies regarding the antigenic specificity of IgM will probably provide further insights on IgM and phospholipid interactions.
Granel
B
B
Service de médecine interne, hôpital de la Timone, CHU, Marseille, France.
Serratrice
J
J
Hubert
A M
AM
Volot
F
F
Pache
X
X
Swiader
L
L
Rossi
P
P
Disdier
P
P
Weiller
P J
PJ
D000328:Adult; D017152:Antibodies, Antiphospholipid / Q000097:blood*; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007132:Immunoglobulin Isotypes / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D010714:Phosphatidylethanolamines / Q000276:immunology*; D012016:Reference Values
D017152:Antibodies, Antiphospholipid; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D010714:Phosphatidylethanolamines