­­­ Background/Purpose: We have recently reported that 70% of an unselected FM cohort (n = 107) had subtle laboratory findings of Primary Immune Deficiency (PID), usually consisting of one or more immunoglobulin subclass deficiencies (Arthritis Rheum 2014;55(11): S905). To better understand this finding we surveyed a second cohort of FM subjects for laboratory evidence of PID, and – additionally – any clinical evidence of recurrent infections. Our results are reported here.

Methods: We retrospectively reviewed serum Ig concentration values on all FM subjects seen between December 2013 and May 2017 in an outpatient, rheumatology office setting. No other diagnosis precluded inclusion in the study unless it was likely that it might predispose to Ig deficiency. A total of 81 consecutive FM subjects, meeting 2010 ACR criteria, were screened; 4 were excluded (i.e., alcohol abuse; prior cancer chemotherapy; age < 18 yrs.). Data on 77 remaining FM subjects were reviewed; 43 of these had coincident RA (26 % seropositive). Ig deficiency was defined as an Ig value below the lower limits of normal (LLN) suggested by PaulÕs Fundamental Immunology ( ); all deficient specimens were tested in duplicate. Ig abnormalities were confirmed by repeat analysis 6 – 9 weeks later. We also reviewed the prevalence of deficient or low mannose binding lectin in these subjects (deficient < 50 ng/ml; low < 500 ng/ml). In an attempt to further ascertain the role of Ig deficiency in FM we also studied the prevalence of any Ig level > LLN but within the lower most quartile of normal values (range / 4). We also collected data regarding a ÒLifetime History of InfectionsÓ on all FM subjects and 26 ÒApparently HealthyÓ aged-matched, community volunteers (± 5 years).

Results: Our findings are listed below:

Serum Ig Deficiency in 77 FM Subjects Compared to Literature Based Controls

Schroeder HW, et al: Immunoglobulin Structure and Function. In Fundamental Immunology. 7^th Ed.

Ed: Paul, WE. Lippincott, New York 2013. Analysis was by Chi-square test.

Of 71 FM subjects in whom Mannose Binding Lectin (MBL) was measured 18 (23 %) had levels <500 ng/ml, and 12 (16%) had levels <50 ng/ml. The prevalence any Ig in FM subjects being within our estimate of PaulÕs ( ) lowest quartile for normal Ig levels ranged from 40% to 74%. There was no significant difference in the prevalence of Ig deficiency in FM subjects with concomitant RA compared to those without RA. A history of recurrent sinus infections was not significantly more common in our FM subjects compared to controls, but a history of recurrent serious, non-sinus infections was more prevalent for FM (P(1) = 0.009), and FM + RA (P(1) = < 0.0001).

Conclusion: Our study shows that clinically significant Ig deficiency, particularly IgG subclass deficiency, is a common accompaniment to FM. It also strengthens the argument that FM may be a disorder associated with immune dysregulation. The precise mechanism of this interaction remains unclear, but deserves further investigation.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/unexpectedly-high-prevalence-of-immunoglobulin-deficiency-in-fibromyalgia-ii/