Abstract 475: Circulating Immunoglobulins Are Not Associated With Intraplaque Mast Cell Number and Other Vulnerable Plaque Characteristics in Patients With Carotid Artery Stenosis

Abstract

Background: Atherosclerosis is a chronic systemic inflammatory disease in which many immune cells participate. Recently we have shown that mast cell numbers are associated with atherosclerotic plaque vulnerability and interestingly with future cardiovascular events (S. Willems et.al. 2013). The endogenous trigger that activates mast cells within the lesion remains unidentified. We hypothesized that mast cells are activated via receptors for IgG and/or IgE. In this study we aimed to establish whether specific immunoglobulin levels in plasma of atherosclerotic patients were related to intraplaque mast cell numbers. In addition, the levels were related to other vulnerable plaque characteristics and baseline clinical data. Results: Serum levels of total IgG, total IgE and oxLDL specific IgG were determined in 135 patients that underwent carotid endarterectomy. The studied patient population with a mean age of 67 and a male prevalence (71%) reflects a relatively typical population of patients with vascular occlusive diseases. The majority of patients were symptomatic (74%) as illustrated by the incidence of amaurosis fugax, a TIA or a stroke. No associations were observed between either the serum immunoglobulin levels or the total mast cell numbers in atherosclerotic plaques (total IgG vs. total mast cells r= -0,038, p=0.664) (tIgE vs total mast cells r=-0.038, p=0.664) (oxLDL-IgG vs total mast cells r=0.137 p=0.114). Furthermore, no associations were found between immunoglobulin levels and the following plaque characteristics: lipid core size, degree of calcification, number of macrophages or smooth muscle cells, amount of collagen and number of microvessels. Interestingly, we observed a negative association between statin use and total IgE (97.5 [43.1-276.8] vs. 157.3 [75.2-545.4] ng/mL, p=0.012) and statin use and oxLDL-IgG (288 [224-406] vs. 399 [282-584] mU/mL, p=0.004). Conclusions: In patients suffering from carotid artery disease, total IgG or IgE and oxLDL-IgG levels do not associate with plaque mast cell numbers or vulnerable plaque histopathological characteristics These data may indicate that other endogenous factors activate mast cells within the atherosclerotic plaque.