Cell-free antigens from precocious Paracoccidioides brasiliensis culture induce a typical delayed-type hypersensitivity reaction

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Optimization of a mouse immunization protocol with Paracoccidioides brasiliensis antigens

The objectives of the present study were to optimize the protocol of mouse immunization with Paracoccidioides brasiliensis antigens (Rifkind's protocol) and to test the modulation effect of cyclophosphamide (Cy) on the delayed hypersensitivity response (DHR) of immunized animals. Experiments were carried out using one to four immunizing doses of either crude particulate P. brasiliensis antigen or yeast-cell antigen, followed by DHR test four or seven days after the last immunizing dose. The data demonstrated that an immunizing dose already elicited response; higher DHR indices were obtained with two or three immunizing doses; there were no differences between DHR indices of animals challenged four or seven days after the last dose. Overall the inoculation of two or three doses of the yeast-cell antigen, which is easier to prepare, and DHR test at day 4 simplify the original Rifkind's immunization protocol and shorten the duration of the experiments. The modulation effect of Cy on DHR was assayed with administration of 2.5, 20 and 100 mg/kg weight at seven day intervals starting from day 4 prior to the first immunizing dose. Only the treatment with 2.5 mg Cy increased the DHR indices. Treatment with 100 mg Cy inhibited the DHR, whereas 20 mg Cy did not affect the DHR indices. Results suggest an immunostimulating effect of low dose of Cy on the DHR of mice immunized with P. brasiliensis antigens.

Use of crude, FML and rK39 antigens in ELISA to detect anti-Leishmania spp. antibodies in Felis catus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Immunodominant Antigens of Leishmania chagasi Associated with Protection against Human Visceral Leishmaniasis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Leishmanial antigens in the diagnosis of active lesions and ancient scars of American tegumentary leishmaniasis patients

Cutaneous biopsies (n = 94) obtained from 88 patients with American tegumentary leishmaniasis were studied by conventional and immunohistochemical techniques. Specimens were distributed as active lesions of cutaneous leishmaniasis (n = 53) (Group I), cicatricial lesions of cutaneous leishmaniasis (n = 35) (Group II) and suggestive scars of healed mucosal leishmaniasis patients (n = 6) (Group III). In addition, active cutaneous lesions of other etiology (n = 24) (Group C1) and cutaneous scars not related to leishmaniasis (n = 10) (Group C2) were also included in the protocol. Amastigotes in Group I biopsies were detected by routine histopathological exam (30.2%), imprint (28.2%), culture (43.4%), immunofluorescence (41.4%) and immunoperoxidase (58.5%) techniques; and by the five methods together (79.3%). In Group II, 5.7% of cultures were positive. Leishmanial antigen was also seen in the cytoplasm of macrophages and giant cells (cellular pattern), vessel walls (vascular pattern) and dermal nerves (neural pattern). Positive reaction was detected in 49 (92.5%), 20 (57%) and 4 (67%) biopsies of Groups I, II and III, respectively. Antigen persistency in cicatricial tissue may be related to immunoprotection or, on the contrary, to the development of late lesions. We suggest that the cellular, vascular and neural patterns could be applied in the immunodiagnosis of active and cicatricial lesions in which leishmaniasis is suspected.

Evaluation of different immunization protocols with P. brasiliensis antigens in Guinea pigs

O objetivo deste trabalho foi desenvolver protocolo eficiente e reprodutível de imunização em cobaias com antígenos de P. brasiliensis, visando a obtenção de modelo experimental para futuros estudos de mecanismos de proteção imunológica. Testaram-se três diferentes antígenos (particulado, solúvel e composto) e seis protocolos nos quais foram avaliadas as influências dos seguintes fatores: presença ou ausência de adjuvante completo de Freund, número de doses imunizantes e intervalo de tempo entre a última dose imunizante e o desafio. A eficiência do protocolo de imunização foi estudada pela avaliação da resposta imune celular e humoral anti-P. brasiliensis, utilizando teste cutâneo e teste de inibição da migração do macrófago, e imunodifusão, respectivamente. Observou-se que: 1. Três doses imunizantes de antígeno induziram melhor resposta do que duas doses; 2. Maior resposta imune foi conseguida com a utilização de adjuvante completo de Freund; 3. Animais desafiados depois de longo tempo (6 semanas) da última dose imunizante mostraram melhor resposta imune anti-P. brasiliensis; 4. Os antígenos solúvel e composto foram igualmente eficientes induzindo maior resposta imune humoral e celular anti-P. brasiliensis enquanto que o antígeno particulado provocou menor reatividade

CROSS-REACTIVITY BETWEEN HARD TICK ANTIGENS

1. The present study was carried out to determine the target cells and tissues for anti-tick immunoglobulins using an indirect immunohistochemical technique.2. Sections in triplicate prepared from unfed ticks Rhipicephalus appendiculatus, R. evertsi and Amblyomma variegatum were used to assess the cross-reactivity of serum from guineapigs naturally infested with these tick species or immunized against them.3. The sections showed slight (+) to strong (++++) labelling of several structures in the tick body, e.g. salivary gland, gut lumen and malpighian tubules, depending on the serum used.4. The immune serum resulting from the immunization of guinea pigs with an extract of unfed nymphs of R. appendiculatus ticks showed the most intense cross-reactivity with the sections examined.

Cellular immune responses in mice immunized with Anisakis simplex larval antigens

Cellular immune responses to Anisakis simplex L3 antigens were investigated in BALB/c mice injected subcutaneously with a homologous crude extract (CE). Popliteal lymph nodes (PLN) were found to be increased in size and weight after A. simplex CE footpad injection. The effects of A. simplex CE in vitro proliferation were assayed with non-fractionated PLN cells or nylon-wool purified T cells derived from pooled lymph node cells of mice subcutaneously injected with CE. Spleen cells from immunized animals (antigen alone, or larva alone, or antigen plus larva) were studied by flow cytometry. The immunization induced a high proportion of CD4 + and TCR alpha beta + T cells. The number of B cells (CD45 + and TCR alpha beta-) in pre-immunized and infected mice was lower than that observed in animals subjected to infection only. The number of CD4 + T cells increased in the infected and in the pre-immunized and infected mice. In the latter, a decrease of CD8a + T cells was noted. The greatest increase in CD8a+ and TCR alpha beta- T cells was found in mice that had been subjected to infection only. Histological analysis showed that the most prominent lesions were gastric and intestinal in animals infected orally with one larva.

Cross-reactivity between antigens from Amblyomma cajennense and A-hebraeum (Acari : Ixodidae)

Laboratory animals exposed to feeding ticks develop resistance which is reflected by a decline in tick engorgement weight, egg-laying by adults and reduced egg viability. Serum antibodies from these hosts and their reaction with tick antigens have been detected by different methods, including precipitation techniques, immunofluorescent techniques, ELISA and Western blots. However, little is known about the effects of antibodies on ticks that engorge on resistant hosts, or which tissues of the tick body are possibly immunogenic. Some researchers, using immunohistochemistry, have detected host antibodies in the gut, salivary glands and haemolymph of ticks engorged on resistant animals. The same technique has helped considerably in determining antigenic sites or antibody targets in other arthropods. Consequently, immunohistochemistry techniques were used in this study to detect cross-reactivity between sera raised against Amblyomma cajennense (Fabricius, 1787) with Amblyomma hebraeum (Koch, 1844), and vice versa. The results show the existence of shared antigens between the 2 tick species. In general, our results point more to a 1-way cross-reactivity of A. hebraeum with A. cajennense than a reciprocal cross-reactivity, suggesting that A. hebraeum is more immunogenic than A. cajennense.