OBJETIVO: Estudar a produção de anticorpos a antígenos polissacarídicos em pacientes com ataxia-telangiectasia CASUÍSTICA E MÉTODO: Utilizando a técnica de ELISA, determinamos os níveis de IgG aos sorotipos 1, 3, 5, 6B, 9V e 14 do pneumococo em 14 pacientes com ataxia-telangiectasia, antes e após a imunização com a vacina pneumocócica 23-valente. Resposta adequada a cada sorotipo foi definida como IgG > 1,3 µg/ml ou o incremento de quatro vezes dos níveis pós em relação aos pré-imunização. RESULTADOS: Seis pacientes (43%) não responderam a todos os sorotipos analisados, quatro a apenas um sorotipo, um paciente a dois, dois a três e apenas um paciente a quatro dos seis sorotipos analisados. Nenhum paciente apresentou resposta adequada a todos os sorotipos testados. Os níveis de IgG ao pneumococo pós-imunização foram superiores aos pré-imunização para todos os sorotipos testados, exceto o 3. Apesar disso, os valores médios pós-imunização foram inferiores a 1,3 µg/ml para todos os sorotipos analisados, exceto o 14. A média de incremento da resposta foi inferior a quatro para todos os sorotipos analisados. CONCLUSÃO: Nossos resultados sugerem que pacientes com ataxia-telangiectasia têm grande risco de apresentar resposta inadequada ao pneumococo, o que pode ser uma das causas das infecções sinopulmonares de repetição.

OBJECTIVE: To analyze the production of antibodies to polysaccharide antigens in patients with ataxia-telangiectasia. PATIENTS AND METHODS: We used the ELISA technique to measure the levels of IgG antibodies to serotypes 1, 3, 5, 6B, 9V and 14 of Streptococcus pneumoniae in 14 patients with ataxia-telangiectasia before and after immunization with 23-valent polysaccharide vaccine. Adequate response to individual polysaccharide can be defined as a postimmunization antibody titer equal to or greater than 1.3 µg/ml or as a minimum fourfold increase over the baseline (preimmunization) value. RESULTS: Six (43%) patients showed an absent response to all serotypes analyzed. Four patients showed adequate response to only one serotype, one patient to two serotypes, two patients to three serotypes and only one patient to four out of six serotypes analyzed. No patient had adequate response to all serotypes tested. Postimmunization pneumococcus IgG levels were higher than preimmunization levels to all serotypes analyzed, except for serotype 3. In spite of this, the mean postimmunization levels were lower than 1.3 µg/ml in all serotypes, except for serotype 14. Mean increment was less than four in all serotypes analyzed. CONCLUSION: Our results suggest that patients with ataxia-telangiectasia are at a high risk of having an impaired response to pneumococcus, which may be one of the causes of recurrent sinopulmonary infections in these patients.

É relatado o caso de uma menina de sete anos de idade com infecções de vias aéreas de repetição (otites, pneumonias e sinusites) desde os cinco meses de vida. A avaliação imunológica demonstrou produção inadequada de anticorpos ao Streptococcus pneumoniae após imunização para todos os sorotipos (1, 3, 5, 6, 9 e 14) testados, embora a paciente apresentasse níveis normais de imunoglobulinas. A avaliação radiológica, no momento da admissão, demonstrou presença de atelectasias difusas associadas a bronquiectasias. Após início do tratamento com imunoglobulina endovenosa e fisioterapia respiratória houve esvaecimento gradual até reversão das alterações radiológicas. Demonstrou-se, assim, a importância de um diagnóstico preciso para início de tratamento específico, com melhora gradual do quadro clínico e radiológico, evitando seqüelas pulmonares irreversíveis.

The authors report the case of a 7-year-old girl, with a history of recurrent respiratory infections since five months of age. Immunological evaluation at four years of age revealed a normal level of total serum immunoglobulins, but a deficient humoral response to Streptococcus pneumoniae. Although having all normal IgG subclasses, the patient had inadequate antibody levels to all serotypes tested (1, 3, 5, 6, 9, and 14). Concurrent radiological evaluation showed diffuse atelectasis and bronchiectasis. Patient was started on IVIG, and subsequent chest CT scan revealed resolution of the above-mentioned lesions. To prevent irreversible damage to lung parenchyma, due to recurrent lower respiratory infections, it is important to identify immunocompromised individuals and treat them accordingly.

The few studies already published about phagocyte functions in Chediak-Higashi syndrome (CHS) has stated that neutrophils present slow rate of bacterial killing but normally ingest microorganisms. In the present study, both phagocytosis and killing of Staphylococcus aureus were verified to be in neutrophils from two patients with CHS when these functions were simultaneously evaluated by a fluorochrome phagocytosis assay. Electron microscopic examination showed morphologic differences among neutophils from CHS patients and normal neutrophils regarding the cytoplasmic structures and the aspects of the phagolysosomes. It was noteworthy the presence of giant phagolysosomes enclosing bacteria in active proliferation commonly observed in CHS neutrophils after 45 min of phagocytosis, wich corresponded with the impaired bactericidal activity of these leukocytes. The present results suggest that phagocytosis may also be defective in CHS, and point out to the sensitivity of the fluorochrome phagocytosis assay and its application in clinical laboratories.