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 TCRalphabeta + T cells. The number of B cells (CD45 + and TCRalphabeta-) 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 TCRalphabeta- 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.

Control of parasitic infections among school children in the peri-urban area of Botucatu, São Paulo, Brazil.

The prevalence of intestinal parasitosis was investigated in a primary school located in Rubião Júnior, a peri-urban district of Botucatu, São Paulo state, Brazil, in order to assess the effect of treatment and practical measures of prophylaxis in the control of parasitic infections among 7-to-18-year-old school children of a low socio-economic status. The first series of parasitological examinations included 219 school children, of which 123 (56.1%) were found to be infected with one or more parasite species. Eighty-four children carrying pathogenic parasites were submitted to various anti-parasitic treatment schedules. We re-evaluated 75 (89%) students after 4 to 6 months post-chemotherapy. The results indicate that the combination of treatment with prophylactic measures has been successful in the control of parasitic infections, since reinfection rates were generally low (< or = 5.3%), except for Giardia lamblia infections (18.6%), and a marked reduction on the prevalence rates was observed with a significant percentage of cure (> or = 73.1%) in children infected with most parasite species. The reasons for the apparent failure in the control of infections caused by Hymenolepis nana and Strongyloides stercoralis are discussed.

New Zealand black mice are immunologically resistant to high-dose, but not low-dose Leishmania mexicana infection.

The course of infection following s.c. inoculation of a wide dose range of L. mexicana stationary-phase promastigotes (SPP) was examined in sexually mature and immature NZB mice of both sexes. Infection with a high dose (greater than 10(7) SPP) was able to induce a protective in vivo response, which could be adoptively transferred with parasite-immune T cells, into naive, syngeneic recipients. In contrast, s.c. infection with a low dose (less than 10(7) SPP) induced non-healing lesions; disease susceptibility could also be transferred into naive animals with T cells from non-immune donors. When the ability to mount a delayed-type hypersensitivity (DTH) reaction was tested in these two groups, the high-parasite dose group gave a significantly higher response. The in vivo protection and high DTH response were reflected in the ability of cells derived from the high-dose resistant (but not low-dose susceptible) mice to mount an antigen-specific T cell response in vitro. The possible immunological effector mechanisms underlying high-dose resistance and low-dose susceptibility are discussed.

Quantitative study of Leishmania braziliensis braziliensis reactive T cells in peripheral blood and in the lesions of patients with American mucocutaneous leishmaniasis.

A limiting dilution analysis (LDA) was utilized to estimate the frequency of L. braziliensis braziliensis reactive T cells (Lbb-T cells) in peripheral blood and in the lesions of patients with mild localized cutaneous leishmaniasis (LCL) or with severe mucosal leishmaniasis (MCL). The frequencies of Lbb-T cells in peripheral blood varied from 1:107300 to 1:3587 and were not significantly different in MCL and LCL patients. However, a significant difference was encountered (P less than 0.02) between the T cells frequencies in cutaneous (1:748 to 1:45) and mucosal lesions (1:152 to 1:13). A positive correlation was also observed between these frequencies and the magnitude of delayed-type hypersensitivity (DTH) (P less than 0.01) and the presence of fibrinoid necrosis and granulomatous reaction in the site of the lesions (P less than 0.05). The lack of correlation between the severity of disease (MCL or LCL) and the frequency of Lbb-T cells in peripheral blood gave no indications towards understanding the physiopathology of severe or mild disease. However, the correlation between high T cell frequencies in the site of the lesions, the magnitude of DTH, the fibrinoid necrosis and the severity of the disease (MCL lesions) points to the possibility that the presence of a strong T cell dependent cellular immune response in the site of the lesions may have a deleterious effect. However, a local well modulated T cell immune response might provide healing of the lesions.

Quantification of Leishmania-specific T cells in human American cutaneous leishmaniasis (Leishmania braziliensis braziliensis) by limiting dilution analysis.

Limiting dilution analysis was used to estimate the frequency of Leishmania-specific T cells from the peripheral blood of 18 human cases of American Cutaneous Leishmaniasis (ACL). Sixteen patients had localized cutaneous leishmaniasis (LCL) and two were recovered LCL patients. In 10 patients with active disease and in two with healed lesions the Leishmania-specific T cell frequencies ranged from 1/10(5) to 1/10(3). In six patients no proliferation was detected after 21 days of cell culture. This finding points to very low precursor frequencies in the peripheral blood of these patients. A significant correlation was found between the two groups with low or high Leishmania-specific T cell frequencies and the lymphoproliferative responses to leishmanial antigens. The majority of the blast-like Leishmania-specific T cells showed a helper/inducer (CD4) phenotype.

Generation of Leishmania-specific short-term T-cell lines derived from peripheral blood of cured American cutaneous leishmaniasis patients.

The putative protective immune response in localized cutaneous leishmaniasis caused by Leishmania braziliensis braziliensis (Lbb) was analysed by generation of short term T-cell lines from peripheral blood lymphocytes (PBL) of three patients. All had had active skin lesions but were clinically cured at the time of study. PBL were stimulated in vitro with sonicated Lbb promastigotes; blasts were isolated after 5 days and propagated for 9 to 16 days before being tested for proliferative capacity. The majority of propagated cells were T4-positive and reacted with Leishmania antigens. An apparent cross-reactivity with Trypanosoma cruzi (T. cruzi) soluble antigen was recorded. Although preliminary, these data indicate that immune T cells derived from cured LCL patients can recognize antigens common to Lbb and T. cruzi.