Background: Patients with predominantly antibody deficiency (PAD) suffer from severe and recurrent infections that require lifelong immunoglobulin replacement and prophylactic antibiotic treatment. Disease incidence is estimated to be 1:25,000 worldwide, and up to 68% of patients develop non-infectious complications (NIC) including autoimmunity, which are difficult to treat, causing high morbidity, and early mortality. Currently, the etiology of NIC is unknown, and there are no diagnostic and prognostic markers to identify patients at risk.Objectives: To identify immune cell markers that associate with NIC in PAD patients.Methods: We developed a standardized 11-color flow cytometry panel that was utilized for in-depth analysis of B and T cells in 62 adult PAD patients and 59 age-matched controls.Results: Nine males had mutations in Bruton's tyrosine kinase (BTK) and were defined as having X-linked agammaglobulinemia. The remaining 53 patients were not genetically defined and were clinically diagnosed with agammaglobulinemia (n = 1), common variable immunodeficiency (CVID) (n = 32), hypogammaglobulinemia (n = 13), IgG subclass deficiency (n = 1), and specific polysaccharide antibody deficiency (n = 6). Of the 53, 30 (57%) had one or more NICs, 24 patients had reduced B-cell numbers, and 17 had reduced T-cell numbers. Both PAD–NIC and PAD+NIC groups had significantly reduced Ig class-switched memory B cells and naive CD4 and CD8 T-cell numbers. Naive and IgM memory B cells, Treg, Th17, and Tfh17 cells were specifically reduced in the PAD+NIC group. CD21lo B cells and Tfh cells were increased in frequencies, but not in absolute numbers in PAD+NIC.Conclusion: The previously reported increased frequencies of CD21lo B cells and Tfh cells are the indirect result of reduced naive B-cell and T-cell numbers. Hence, correct interpretation of immunophenotyping of immunodeficiencies is critically dependent on absolute cell counts. Finally, the defects in naive B- and T-cell numbers suggest a mild combined immunodeficiency in PAD patients with NIC. Together with the reductions in Th17, Treg, and Tfh17 numbers, these key differences could be utilized as biomarkers to support definitive diagnosis and to predict for disease progression.

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Vaccine adjuvants stimulate the innate immune system and determine the outcome of the immune response induced. A better understanding of their action is therefore crucial to the development of new and safer vaccines. Monophosphoryl lipid A (MPL), a 'detoxified' version of lipolysaccharide, is a promising new adjuvant component in human vaccines. The present study uses an ovine lymphatic cannulation model to study cell recruitment and antigen transport from the injection site into the afferent lymph, and how this is modulated by co-injection with MPL. Compared with saline, MPL injections caused only minor variations in lymph flow and no difference in cell number migrating into the lymph. MPL did, however, cause a significantly increased recruitment of neutrophils and monocytes, but not dendritic cells (DC) into the lymph for the first 12 h. Soluble ovalbumin (OVA) antigen flowed freely into the lymph over a 24-h period and was slightly reduced at 6-9 h in the MPL-injected sites. OVA-coated fluorescent 1-l beads were initially transported predominantly by neutrophils and, from 24 to 72 h, by DC. MPL induced an increased and more sustained transport of beads by neutrophils and monocytes although it did not increase the phagocytic capacity of these cells. In contrast to aluminium adjuvant, MPL did not increase bead transport by DC at the later time point. These studies provide important new insights in the in vivo action of different adjuvants and the initial events that set up an immune response after vaccination. Keywords: adjuvant; afferent lymph; dendritic cells; innate immunity; monocytes; neutrophils Vaccine adjuvants are now recognised as essential stimulators of the innate immune system that help drive the strength and type of the adaptive immune response generated. This recent understanding has highlighted the need for a greater understanding of the effects of adjuvants in vaccine research and development. Monophosphoryl lipid A (MPL) is a promising new adjuvant that was recently approved for use in human viral vaccines, 1,2 has been shown to enhance allergen-specific immunotherapy 3 and is being actively investigated as a component in cancer vaccine strategies. 4 MPL is a modified and 'detoxified' version of bacterial lipolysaccharide (LPS). Although LPS is a potent immunostimulator, its unacceptable side effects have limited its clinical use. MPL retains many of the immunostimulatory effects of the parent LPS molecule; however it shows a reduced inflammatory profile. 2 Both MPL and LPS activate the toll like receptor 4 signalling pathway. 2 Toll like receptor 4 signalling induces the processing and presentation of antigen by maturing cells into antigen-presenting cells such as dendritic cells (DCs), and upregulates many of the processes involved in antigen presentation and migration. 5 It is the sum of all these effects that determines the extent of inflammation and effective immunity generated after vaccination. 6 After infection or injection of a vaccine, innate cells derived from the tissue or periph...

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