Factor XIm, the clotting factor essential for covalent stabilization of the fibrin clot, is a heterodimer consisting of a2 and b2 subunits, with catalytic function residing in the a-chain. In order to address questions regarding sites of synthesis and chromosomal localization of the Factor XIII a-chain, cDNA was cloned from a Xgtll human placental cDNA library. Nucleotide and amino acid sequences were determined from the cDNA. Amino acid sequencing of purified platelet Factor XIII a-chains confirmed the authenticity of the Xgtll clone. The gene for Factor XIII achain was mapped uniquely to chromosome 6. Northern blot analysis of human placental and U937 (monocytelike) cell poly (A)' mRNA showed a single -4.0-kb message for the Factor XIII a-chain. These results provide conclusive evidence that the a-chain is synthesized by placenta and monocyte cell lines.

We describe a 65-year-old Thai woman who developed cytomegalovirus retinitis (CMVR) in the setting of Good syndrome—a rare, acquired partial immune deficiency caused by thymoma. The patient subsequently developed vitritis with cystoid macular edema (CME) similar to immune recovery uveitis (IRU) despite control of the retinitis with antiviral agents. A comprehensive review of the literature through December, 2014, identified an additional 279 eyes of 208 patients with CMVR in the absence of human immunodeficiency virus (HIV) infection. Including our newly reported case, 9 of the 208 patients (4.3 %) had Good syndrome. Twenty-one of the 208 patients (10.1 %) had CMVR related to intraocular or periocular corticosteroid administration. The remaining 178 patients (85.6 %) acquired CMVR from other causes. Within the subset of patients who did not have Good syndrome or did not acquire CMVR followed by intraocular or periocular corticosteroid administration, there were many other factors contributing to a decline in immune function. The most common included age over 60 years (33.1 %), an underlying malignancy (28.7 %), a systemic autoimmune disorder requiring systemic immunosuppression (19.1 %), organ (15.2 %) or bone marrow (16.3 %) transplantation requiring systemic immunosuppression, and diabetes mellitus (6.1 %). Only 4.5 % of the patients had no identifiable contributor to a decline in immune function. While the clinical features of CMVR are generally similar in HIV-negative and HIV-positive patients, the rates of moderate to severe intraocular inflammation and of occlusive retinal vasculitis appear to be higher in HIV-negative patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s12348-016-0070-7) contains supplementary material, which is available to authorized users.

Factor XIII is the fibrin-stabilizing factor that covalently cross- links fibrin monomers to form a highly organized, stable fibrin clot. The plasma form of factor XIII is a heterodimer, a2b2, consisting of two a-chains and two b-chains; the intracellular form, such as in platelets and placenta, is a dimer, a2, consisting of a-chains only. The catalytic function of factor XIII, a transglutaminase, resides in the a-chain. To address questions regarding sites of synthesis of factor XIII a-chain, an EcoRI restriction fragment from the protein- coding region of the factor XIII a-chain cDNA was used as a probe for Northern blot analysis. The cDNA probe showed hybridization with a single approximately 4.0-kilobase (kb) message in poly (A)+ mRNA prepared from normal human peripheral blood monocytes and normal human liver. The results demonstrate conclusively that factor XIII a-chains are actively synthesized in circulating monocytes and in liver. To our knowledge, these data represent the first demonstration of synthesis of any blood coagulation factor in primary uncultured and unstimulated monocytes or macrophage cells.