Increased immunoglobulin G anti-Paracoccidioides brasiliensis serum antibody avidity as a predictor of favorable posttherapeutic evolution in paracoccidioidomycosis.

Paracoccidioidomycosis is endemic in Latin America, and ca. 80% of all cases occur in Brazil. Little is known about antibody avidity or the evolution of such avidity in the posttherapeutic period for the different clinical presentations of the disease. In the present study, we evaluated 53 patients with paracoccidioidomycosis and calculated the avidity index. Medium- and high-avidity antibodies were found in 79.5% of patients with chronic presentation (n = 39). Among patients with the acute form (n = 14), 57.1% of the antibodies presented low avidity. In the posttherapeutic period, there was a significant increase in antibody avidity in patients presenting with the chronic multifocal form. In our preliminary study, which needs to be confirmed using a larger number of samples, the optimized method for studying antibody avidity detected differences among the clinical presentations of the mycosis and indicated the value of the avidity index as a marker of posttherapeutic evolution of patients with a multifocal chronic form of the disease.

T-cell recognition of Paracoccidioides brasiliensis gp43-derived peptides in patients with paracoccidioidomycosis and healthy individuals.

Vaccines with synthetic peptides induce the immune response to epitopes that bind to several HLA alleles. By using a TEPITOPE algorithm, we selected and analyzed the T-cell responses of peripheral blood mononuclear cells from 29 paracoccidioidomycosis (PCM) patients to peptides of the immunodominant gp43 antigen of Paracoccidioides brasiliensis, the causative agent of PCM.

In silico prediction of peptides binding to multiple HLA-DR molecules accurately identifies immunodominant epitopes from gp43 of Paracoccidioides brasiliensis frequently recognized in primary peripheral blood mononuclear cell responses from sensitized individuals.

One of the major drawbacks limiting the use of synthetic peptide vaccines in genetically distinct populations is the fact that different epitopes are recognized by T cells from individuals displaying distinct major histocompatibility complex molecules. Immunization of mice with peptide (181-195) from the immunodominant 43 kDa glycoprotein of Paracoccidioides brasiliensis (gp43), the causative agent of Paracoccidioidomycosis (PCM), conferred protection against infectious challenge by the fungus. To identify immunodominant and potentially protective human T-cell epitopes in gp43, we used the TEPITOPE algorithm to select peptide sequences that would most likely bind multiple HLA-DR molecules and tested their recognition by T cells from sensitized individuals. The 5 most promiscuous peptides were selected from the gp43 sequence and the actual promiscuity of HLA binding was assessed by direct binding assays to 9 prevalent HLA-DR molecules. Synthetic peptides were tested in proliferation assays with peripheral blood mononuclear cells (PBMC) from PCM patients after chemotherapy and healthy controls. PBMC from 14 of 19 patients recognized at least one of the promiscuous peptides, whereas none of the healthy controls recognized the gp43 promiscuous peptides. Peptide gp43(180-194) was recognized by 53% of patients, whereas the other promiscuous gp43 peptides were recognized by 32% to 47% of patients. The frequency of peptide binding and peptide recognition correlated with the promiscuity of HLA-DR binding, as determined by TEPITOPE analysis. In silico prediction of promiscuous epitopes led to the identification of naturally immunodominant epitopes recognized by PBMC from a significant proportion of a genetically heterogeneous patient population exposed to P. brasiliensis. The combination of several such epitopes may increase the frequency of positive responses and allow the immunization of genetically distinct populations.

Trombocitopenias: diagnóstico diferencial e evoluçäo / Thrombocytopenia: differential diagnosis and evolution

O objetivo do presente estudo foi constatar a prevalência de trombocitopenia na populaçäo de doenças hematológicas, o diagnóstico diferencial, a conduta terapêutica e a evoluçäo clínica. Foram estudados 191 pacientes adultos, trombocitopênicos atendidos no CHSP, de janeiro a julho de 1997, com estudos retrospectivos e prospectivo, de 65 homens e 126 mulheres. Nestes pacientes, além do hemograma, plaquetas e hemossedimentaçäo, foram realizados exames subsidiários que permitiram determinar a doença básica. Foram excluídos as trombocipenias relacionadas a colagenoses, leucemias agudas e quimioterapia anti neoplásica, além das decorrentes de erro de laboratório ou artefato. Os dados revelam que o diagnóstico de Púrpura Trombocitopênica Idiopática é freqüente; a evoluçäo é crônica e a cura pouco provável, mas o controle permite ao paciente levar vida praticamente normal. Näo se utilizou doses elevadas de prednisona, immunoglobina e esplenectomia. Nos pacientes sem diagnóstico e em acompanhamento, a hipótese mais provável é de que a faixa da normalidade é variável por questäo. A presença de hepatopatia englobando hepatite crônica por vírus B e C chama a atençäo pela sua freqüencia em serviços de hematologia. As doenças hematológicas associadas, habitualmente mielodisplasias, tiveram seu diagnóstico confirmado por mielograma e/ou biópsia de medula óssea. A presença de trombocitopenia em pacientes com vírus da Imunodeficiência Humana na maioria dos casos assintomáticos, obriga a inclusäo do teste para o HIV nos pacientes trombocitopênicos assintomáticos. O trabalho pretende demonstrar, que a trombocitopenia é uma situaçäo freqüente na prática hematológica. Os pacientes evoluem com vida normal na maioria dos casos, dependendo da doença de base, e o controle é relativamente simples na Púrpura Trombocitopênica Idiopática.