Background: Recent studies showed that a single injection of human monoclonal allergen‐specific IgG antibodies significantly reduced allergic symptoms in birch pollen‐allergic patients. Since the production of full monoclonal antibodies in sufficient amounts is laborious and expensive, we sought to investigate if smaller recombinant allergen‐specific antibody fragments, that is, nanobodies, have similar protective potential. For this purpose, nanobodies specific for Bet v 1, the major birch pollen allergen, were generated to evaluate their efficacy to inhibit IgE‐mediated responses.Methods: A cDNA‐VHH library was constructed from a camel immunized with Bet v 1 and screened for Bet v 1 binders encoding sequences by phage display. Selected nanobodies were expressed, purified, and analyzed in regards of epitope‐specificity and affinity to Bet v 1. Furthermore, cross‐reactivity to Bet v 1‐homologues from alder, hazel and apple, and their usefulness to inhibit IgE binding and allergen‐induced basophil activation were investigated.Results: We isolated three nanobodies that recognize Bet v 1 with high affinity and cross‐react with Aln g 1 (alder) and Cor a 1 (hazel). Their epitopes were mapped to the alpha‐helix at the C‐terminus of Bet v 1. All nanobodies inhibited allergic patients' polyclonal IgE binding to Bet v 1, Aln g 1, and Cor a 1 and partially suppressed Bet v 1‐induced basophil activation.Conclusion: We identified high‐affinity Bet v 1‐specific nanobodies that recognize an important IgE epitope and reduce allergen‐induced basophil activation revealing the first proof that allergen‐specific nanobodies are useful tools for future treatment of pollen allergy.

(1) Background: There are no reliable and widely available markers of functional iron deficiency (FID) in cancer. The aim of the study was to evaluate the role of transferrin (Tf) as a marker of cancer of the ovary (CrO) and related FID. (2) Methods: The study groups consisted of 118 patients with CrO and 69 control females. Blood serum iron status was determined on a Beckman Coulter AU (USA) analyzer. Tf quantification was performed by immunoturbidimetry. The relative contents of apo- and holo-Tf (iron-free and iron-saturated Tf, respectively) were determined in eight patients and a control female by immunochromatographic analysis based on the use of monoclonal single-domain antibodies (nanobodies). (3) Results: Four groups of patients with different iron statuses were selected according to ferritin and transferrin saturation values: absolute iron deficiency (AID) (n = 42), FID (n = 70), iron overload (n = 4), normal iron status (n = 2). The groups differed significantly in Tf values (p < 0.0001). Lower values of Tf were associated with FID. Furthermore, FID is already found in the initial stages of CrO (26%). Immunosorbents based on nanobodies revealed the accumulation of apo-Tf and the decrease in holo-Tf in patients with CrO. (4) Conclusions: Tf may be a promising tool for diagnosing both CrO and associated FID.