Abstract. Class specific anti‐IgA (anti‐α) antibodies were found in seven out of sixteen patients in whom serum IgA was not demonstrable by the Mancini method (sensitivity down to 0.02 mg/ml). Allotype specific anti‐IgA [anti‐A2m(l)] antibodies were found in an eighth patient. The anti‐IgA antibodies proved to be of the IgG class. In the eight patients with anti‐IgA antibodies, the presence of these antibodies could not be ascribed to immunization by administration of blood products. Isoimmunization in pregnancy and absorption of colostral IgA or animal IgA were other possible causes of anti‐IgA antibodies.–Using a combined IgA/anti‐IgA radioimmunoassay very low IgA levels (0.00013‐0.020 mg/ml) were demonstrable in patients without anti‐IgA antibodies whose serum IgA levels could not be determined by the Mancini method.–IgA metabolism was studied in five IgA‐deficient patients. In two patients the rate of degradation of 132I‐IgA almost equalled that in individuals with a normal serum IgA level. In three patients, however, the rate of degradation was greatly increased. In their sera, in contrast to the first two, class specific anti‐a antibodies were demonstrated.–One of these patients showed an anaphylactic reaction immediately after intravenous injection of mI‐IgA. Only this patient showed complement fixation by the IgA/anti‐IgA complex and IgA stimulation of lymphocytes.–The presence of anti‐IgA antibodies has some important practical implications for those patients who need blood products.

A new sickling hemoglobin (Hb) detected in an Argentinean family from San Martín, Buenos Aires, Argentina, is hereby described. Two mutations were identified on the same β-globin gene resulting in a new variant named Hb San Martin. One mutation was found on exon 1, corresponding to Hb S [β6Glu→Val, GAG>GTG] and the second one on exon 3 at β105(G7)Leu→Pro, CTC>CCC. The replacement of leucine by proline will likely impair the structure breaking helix G and causing instability of the molecule and the clinical manifestations typical of unstable Hbs. The mutation at β105 seemed to be a de novo one in our patients, arising on a previously mutated gene, due to the fact that Hb S is the most frequent structural variant.

Hemoglobin (Hb) Sabine is an unstable Hb variant that causes hemolytic anemia in heterozygous state, with inclusion bodies in the red blood cells (RBC). This hemoglobin is the result of a point mutation at codon 91(CTG)(CCG) of the beta-globin gene. We report, for the first time in South America, the identification of Hb Sabine in a nine-month-old female baby, referred to our laboratory bearing a severe hemolytic anemia. We emphasize the need for the correct characterization of this unstable hemoglobin mainly for therapeutic purposes and for genetic counseling.

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We report a rare a1 globin gene variant (Hb Interlaken) found in a 63-year-old woman of Italian ancestry living in Buenos Aires Province, Argentina. The variant, a missense mutation at cd15 (GGT → GAT) causing a Gly → Asp amino acid substitution and also known as Hb J Oxford, was found in combination with the common thalassemia trait cd 39 (C→T). The clinical picture of the patient was that of a b-thalassemia trait. This work is licensed under a Creative Commons Attribution 3.0 License (by-nc 3.0). ©Copyright I.M. Bragós et al.