Sublingual house dust mite immunotherapy has no impact on decrease of circulating erythrocytes upon airway allergen challenge in allergic rhinitis

Abstract

House dust mite (HDM) allergy is a predominant cause for perennial allergic rhinitis (AR) in Europe. We recently reported that circulating erythrocyte numbers decrease after airway allergen challenge in a murine asthma model and in grass-pollen sensitized AR subjects. Consequently, we aimed to evaluate these findings in HDM sensitized AR subjects and the influence of preceding allergen immunotherapy. Seventy-seven (age 26.8 ± 7.3 years; 54.5% female) HDM-allergic rhinitis subjects previously enrolled in a randomized, monocentric sublingual immunotherapy (SLIT) trial at the Vienna Challenge Chamber (VCC) were included. Subjects had either received placebo (n = 22), low-dose HDM (n = 29) or high-dose HDM specific sublingual immunotherapy (n = 26) daily for 24 weeks. Blood sampling was performed before and after 6 hours of HDM allergen exposure. Overall, specific airway allergen challenge resulted in a significant decrease in circulating erythrocytes and hematocrit (p < 0.001), and elevation of leukocytes (p < 0.001), particularly segmented neutrophils (p < 0.001). Gender had no significant effect on the observed changes in circulating blood cells. Erythrocytes decreased and neutrophil counts increased significantly after airway allergen challenge regardless of preceding immunotherapy. These findings imply a rapid systemic mobilization of neutrophils occurring within immediate type hypersensitivity response upon a specific allergen challenge, which is possibly inversely linked with the erythrocyte numbers.

Hematologic Features of Children and Adolescent Patients with Acute Hypersensitivity Reactions on Drugs and Food

“…Recent publications by G. Jordakieva and coauthors revealed that one of the obscure phenomena, when a causally significant allergen is introduced into a sensitized macroorganism, is a decrease in hemoglobin and erythrocytes [9,10]. However, we failed to find any reports on the characteristic hematological features in the patients with hypersensitivity reactions in clinically manifested syndromes of skin damages and/or anaphylaxis.…”

The impact of allergen exposure and specific immunotherapy on circulating blood cells in allergic rhinitis

“…Serum PF-4 and β-TG levels in HDM AR patients appear to be comparable to those in healthy controls [ 125 ]. Incidentally, we found a significant increase in circulating thrombocytes after 2 h of continuous allergen challenge compared to baseline values [ 8 , 9 ]; however, 4 h after allergen challenge, no significant changes in circulating thrombocyte numbers were observed (data not published). During AIT in grass pollen AR, no changes in platelet activation marker β-TG levels were observed in plasma, even with during administration of the highest vaccine dose [ 126 ].…”

“…Blood neutrophils, particularly segmented neutrophils, increase upon allergen challenge [ 8 , 9 ] and show altered functions in AR. For example, circulating blood neutrophils from AR patients produced more LTB2 after stimulation with calcium ionophore than controls.…”

“…Indeed, circulating leukocytes and their subsets markedly differ in blood of symptomatic AR patients compared to healthy controls [ 5 ] and even an activation of platelets has been reported [ 6 , 7 ]. Recently, we further described a rapid decrease in circulating erythrocytes after allergen exposure in AR [ 8 , 9 ]. Thus, local nasal inflammation upon allergen exposure induces systemic inflammatory responses [ 10 ] and, in the context of effector cell recruitment, activation of bone marrow.…”

Recent Advances in Experimental Allergy

“…HDM are therefore carefully considered with respect to the management and treatment of atopic diseases [9, 10]. Moreover, HDM extracts are frequently used in experimental models in research focused on allergy and atopy [11, 12]. …”