<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0864-0289</journal-id>
<journal-title><![CDATA[Revista Cubana de Hematología, Inmunología y Hemoterapia]]></journal-title>
<abbrev-journal-title><![CDATA[Rev Cubana Hematol Inmunol Hemoter]]></abbrev-journal-title>
<issn>0864-0289</issn>
<publisher>
<publisher-name><![CDATA[Centro Nacional de Información de Ciencias MédicasEditorial Ciencias Médicas]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0864-02892021000100008</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Asociación entre hipoplasia del timo y disminución de inmunoglobulina A]]></article-title>
<article-title xml:lang="en"><![CDATA[Association between thymus hypoplasia and immunoglobulin A reduction]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[de la Guardia Peña]]></surname>
<given-names><![CDATA[Odalis María]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Macias Abraham]]></surname>
<given-names><![CDATA[Consuelo]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ruiz Villegas]]></surname>
<given-names><![CDATA[Laura]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Instituto de Hematología e Inmunología  ]]></institution>
<addr-line><![CDATA[La Habana ]]></addr-line>
<country>Cuba</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>03</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>03</month>
<year>2021</year>
</pub-date>
<volume>37</volume>
<numero>1</numero>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://scielo.sld.cu/scielo.php?script=sci_arttext&amp;pid=S0864-02892021000100008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://scielo.sld.cu/scielo.php?script=sci_abstract&amp;pid=S0864-02892021000100008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://scielo.sld.cu/scielo.php?script=sci_pdf&amp;pid=S0864-02892021000100008&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN El sistema inmune madura gradualmente durante la infancia y el nacimiento es un momento crucial para este proceso. El paso por el canal del parto es el primer estímulo que el sistema inmunitario percibe para comenzar así su maduración progresiva. El timo como órgano linfoide primario, es el primero en aparecer entre todos los órganos linfoides; en este órgano ocurre la ontogenia, diferenciación y maduración de los linfocitos T que migran a los órganos linfoides secundarios como linfocitos T inmunocompetentes. La producción de IgA por los linfocitos B es uno de los mecanismos esenciales de respuesta inmune de las mucosas a las que protege en su forma de IgA secretoria. En el Instituto de Hematología e Inmunología, se atendieron en consulta 62 pacientes pediátricos entre uno y cinco años de edad, con antecedentes de infecciones respiratorias agudas frecuentes, con dos o más episodios en un mes, a los que se les diagnosticó por ultrasonografía una disminución del área tímica (hipoplasia). De ellos, 50 % presentó además disminución de la concentración de IgA en suero. Estos resultados sugieren múltiples interrogantes. Consecuentemente, este trabajo tiene como objetivo presentar la asociación hallada entre la disminución del tamaño del timo y la disminución de la concentración en suero de IgA, en un grupo de niños de uno a cinco años, con antecedentes de infecciones respiratorias frecuentes, consultados en el Instituto de Hematología e Inmunología durante un año.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT The immune system gradually matures during childhood, and birth is a crucial moment in this process. Transit through the birth canal is the first stimulus perceived by the immune system to start its progressive maturation. The thymus, a primary lymphoid organ as it is, is the first lymphoid organ to appear. It is the site of the ontogeny, differentiation and maturation of the T-lymphocytes migrating to secondary lymphoid organs as immunocompetent T-lymphocytes. IgA production by B-lymphocytes is one of the essential immune response actions performed by mucosas, which they protect in the form of secretory IgA. A study was conducted of 62 pediatric patients aged 1-5 years attending consultation at the Institute of Hematology and Immunology who had a history of frequent acute respiratory infection, with two or more episodes in one month. These patients were ultrasonographically diagnosed with thymus size reduction (hypoplasia). Among them, 50% also presented a decrease in serum IgA concentration. These results pose many questions concerning the association between thymus hypoplasia and IgA reduction. The purpose of the study was therefore to present the association found between thymus size reduction and serum IgA concentration decrease in a group of children aged 1-5 years with a history of frequent respiratory infection attending the Institute of Hematology and Immunology during one year.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[hipoplasia]]></kwd>
<kwd lng="es"><![CDATA[timo]]></kwd>
<kwd lng="es"><![CDATA[inmunoglobulinas]]></kwd>
<kwd lng="es"><![CDATA[infecciones respiratorias agudas]]></kwd>
<kwd lng="en"><![CDATA[hipoplasia]]></kwd>
<kwd lng="en"><![CDATA[thymus]]></kwd>
<kwd lng="en"><![CDATA[immunoglobulins]]></kwd>
<kwd lng="en"><![CDATA[acute respiratory infection]]></kwd>
</kwd-group>
</article-meta>
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