Helper T cell immunity in humans with inherited CD4 deficiency.

CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαß+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αß T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.

Cryopyrinopathies: update on pathogenesis and treatment.

Cryopyrinopathies are a group of rare autoinflammatory diseases that includes familial cold autoinflammatory syndrome, Muckle-Wells syndrome and chronic infantile neurologic cutaneous articular syndrome (also termed neonatal-onset multisystemic inflammatory disease). These syndromes were initially considered to be distinct disease entities despite some clinical similarities; however, mutations of the same gene have since been found in all three cryopyrinopathies. These diseases, therefore, are not separate but represent a continuum of subphenotypes. The gene in question, CIAS1 (now renamed NLRP3) encodes NALP3 (also known as cryopyrin). NALP3 is an important mediator of inflammation and interleukin 1beta processing. New therapies based on biologic agents that specifically target interleukin 1beta are currently being developed. These new agents have provided very encouraging results for patients with these long-lasting inflammatory conditions--which used to be considered refractory to treatment. The development of therapeutic options for these cryopyrinopathies illustrates effective translation of basic science to clinical practice and the convergence of human genetics and targeted therapies.

EBV-negative lymphoproliferative disease with hyper-IgA, in a child with combined liver and small bowel transplantation.

A 4-year-old boy presented 14 months after liver and small bowel transplantation with fever, diarrhea, elevated liver enzymes, thrombocytopenia and autoantibodies. Total gammaglobulins level was normal but the level of plasma IgA1 was very high. The blood PCR for Epstein-Barr virus (EBV) was negative. The ileal biopsy disclosed a lymphoplasmacytic infiltration. The EBER probe was negative on the small bowel biopsies. The child was considered as suffering from a non-EBV-induced posttransplant lymphoproliferative disorder (PTLD). The high IgA level was presumed to be secreted by proliferating plasma cells in the transplanted bowel. Immunosuppression was reduced; but the efficacy was incomplete and an anti-CD20 antibody was added. There was complete resolution of symptoms and normalization of the IgA level. As IgA1 is mostly of intestinal origin, this unusual presentation of PTLD should lead to a high suspicion of a small bowel proliferating process.