Predominantly Antibody-Deficient Patients With Non-infectious Complications Have Reduced Naive B, Treg, Th17, and Tfh17 Cells.

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.

The kinetics of soluble and particulate antigen trafficking in the afferent lymph, and its modulation by aluminum-based adjuvant.

Aluminium adjuvants are potent enhancers of immune responses. Despite being a component in most human and animal vaccines, their specific mode of action remains elusive. We have used a sheep lymphatic cannulation model to directly measure the trafficking of soluble and particulate antigen in real-time from the site of injection. Aluminium adjuvant does not alter the kinetics of antigen flow from the site of injection; however it does reduce the amount of soluble antigen entering into afferent lymph. Large numbers of neutrophils, but not DCs, were recruited into the lymph in both saline and aluminium-injected sites and were predominantly responsible for the early uptake of particulate antigen into the lymphatic. Aluminium adjuvant did not significantly increase neutrophil uptake but markedly increased the subsequent uptake of particulate antigen by DCs from 48 to 72 h after antigen injection. Thus, the adjuvanticity of aluminium does not correlate with slow antigen release or increased cell recruitment, but with retention of antigen at the site of injection, and increased uptake of particulate antigen by mature migratory DCs after 24h.