Antiphospholipid antibodies are commonly related to connective tissue disorders, the use of certain drugs, and infection. It is thought that antiphospholipid syndrome (APS) is associated primarily with connective tissue disorders. We describe a healthy young male who had an episode of APS that was associated with cytomegalovirus infection and who developed mesenteric and femoropopliteal thrombosis. He responded well to treatment with anticoagulants; 6 months after the onset of APS, IgM and IgG anticardiolipin antibody titers declined. We point out the importance of screening for infectious agents in cases of APS; if the agents are identified, APS may be transitory.

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In our experience, sonography and especially color-Doppler and power-Doppler sonography was helpful in the diagnosis of CSD. We believe it should be used in the initial study of children with regional lymphadenopathy, and serologic testing should be performed when CSD is suspected.

Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-α2 alone (five patients) or with IFN-ω (eight patients) from a cohort of 279 patients (4.7%) aged 6–73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-α2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-ω. The patients’ autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients <70 yr of age (5.7 vs. 1.1%, P = 2.2 × 10−5), but not >70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-α2 and IFN-ω (OR = 11.7, P = 1.3 × 10−5), especially those <70 yr old (OR = 139.9, P = 3.1 × 10−10). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for ∼5% of cases of life-threatening influenza pneumonia in patients <70 yr old.

(Rev Med Chile 2011; 139: 448-454).