Comparison of Complement Receptor Markers C5aR (CD88) and C3aR on Lymphocyte and Monocyte Subpopulations in Peripheral Blood of Serum IgE Positive and Negative Asthmatic Adults

Objective. C5a and C3a are complement split products (CSPs) and potent anaphylatoxins which are formed through enzymatic cleavage by pollen and dust mite allergens and mast cell tryptase. Previous studies in our laboratory reported that levels of plasma C5a desArg of outpatient adults with asthma correlated with asthma severity and QOL (quality of life) scores. While increased plasma C5a or C5aR+ lymphocytes may mediate increases in serum immunoglobulin (Ig)E, the role of C3aR is unknown. This study sought to evaluate levels of C5aR and C3aR on lymphocytes and monocytes in serum IgE positive (+) and negative (-) adults with asthma. Methods. Blood was obtained from adults with asthma exacerbation (N=24, 16 females, eight males) who required emergency department (ED) treatment. Distributions of lymphocyte (CD3, CD4, CD8, C5aR (CD88), C3aR), monocyte subsets (CD14, C5aR (CD88), C3aR), and serum IgE levels were determined (flow microfluorimetry, fluoro-enzyme immunoassay). Results. In this cohort, serum IgE levels were elevated (908 IU/mL±1209). When subjects were stratified according to serum IgE status, numbers of C3aR+ cells on lymphocytes were higher in serum IgE+ compared with serum IgE- subjects (46.6±5.6, 39.60±7.9; P=0.05). Numbers of CD5aR+ cells on lymphocytes were similar in both groups. Conclusions. The results suggest that C3aR+ lymphocytes may play a role in allergic disease in adults with asthma and elevated serum IgE levels.