Parasite evolution in response to sex-based host heterogeneity in resistance and tolerance.

Heterogenity between sexes in terms of both the level and the type of immune response to infection is documented in many species, but its role on parasite evolution is only beginning to be explored. We adopt an evolutionary epidemiology approach to study how the ability of a host to respond to infection through active immunity (resistance) or through minimizing deleterious effects of a given parasite load (tolerance) affects the evolution of parasite virulence. Consistently with earlier models, we find that increases in host resistance and tolerance both favour more virulent parasite strains. However, we show that qualitatively different results can be obtained if dimorphism between the sexes occurs through resistance or through tolerance depending on the contact pattern between the sexes. Finally, we find that variations in host sex ratio can amplify the consequences of heterogeneity for parasite evolution. These results are analysed in the light of several examples from the literature to illustrate the prevalence of sexually dimorphic immune responses and the potential for further study of the role of sexual dimorphism on parasite evolution. Such studies are likely to be highly relevant for improving treatment of chronic infections and control of infectious diseases, and understanding the role of sex in immune function.

Protection of islets of Langerhans from antibodies by microencapsulation with alginate-poly-L-lysine membranes.

Microencapsulation of islets has been proposed to prevent their immune destruction following transplantation. An indirect immunofluorescence technique has been developed and used to study the permeability of the alginate-poly-L-lysine microcapsules to antibodies. Wistar rat islets were incubated with the R2D6 monoclonal mouse IgM antibody against rat islets, microencapsulated, and incubated with fluorescein-labeled goat IgG antibodies against mouse IgG and IgM. For the negative controls, the first antibody was omitted or both antibodies were omitted. The positive controls included islets incubated with both antibodies before they were encapsulated. Our study demonstrated that the alginate-poly-L-lysine membranes are not permeable to IgG when poly-L-lysine of molecular weights ranging from 21,000 to 390,000 are used. This simple immunofluorescence technique demonstrated the nonpermeability of the microcapsules to IgG, and could be useful for the initial evaluation of new types of membranes.

Recurrent localised pneumonia due to bronchial infiltration in a patient with chronic lymphocytic leukaemia.

A woman with chronic lymphocytic leukaemia developed pneumonia on five occasions in the right middle lobe in the course of 27 months. Bronchoscopy disclosed concentric narrowing of the middle lobe bronchus by leukaemic infiltration.

Characterization of plasma cell populations at autopsy after human allogeneic bone marrow transplantation.

Postmortem fixed tissue sections of the lymphoid and digestive systems of eight consecutive leukemic patients dying of various diseases after bone marrow transplantation (BMT) were analyzed for the presence of the heavy chains gamma, alpha, mu, delta, and epsilon and light chains kappa and lambda, with the use of a standard immunoperoxidase method. Two distinct types of plasma cell populations were found. The first type was a widely distributed polyclonal plasma cell population, lacking IgD-positive plasma cells and germinal centers. The second type of plasma cell population, found in 6 of 8 patients, was a group of monoclonal plasma cell populations positive for the heavy chains gamma, alpha, mu, or delta. Recent immunohistologic observations of the human lymph node suggest that the first type of polyclonal plasma cell population could arise from a nonspecific expansion of sIgM+, sIgD- B lymphocytes. The lack of germinal centers, a structure closely involved in specific-antibody production, may correlate with the poor specific-antibody response documented in patients after BMT. The monoclonal plasma cell populations, found with an unexpectedly high frequency, are probably related to a functional T-cell defect.

Extramedullary plasmacytoma associated with angiofollicular lymph node hyperplasia.

We report a case of hyaline-vascular type of angiofollicular lymph node hyperplasia involving the left pulmonary lymph nodes and lung. It clinically presented as an obstruction of the left lower lobe main bronchus secondary to the development of an extramedullary plasmacytoma in the lesion. An immunoperoxidase stain revealed a monoclonal IgG-lambda pattern of the tumor, contrasting with the polyclonal plasma cell population of the angiofollicular lymph node hyperplasia. This case demonstrates the neoplastic potential of angiofollicular lymph node hyperplasia.

14q+ abnormality with probable t(8;14)(q24;q32) in a young Haitian immigrant with acquired immunodeficiency syndrome and concomitant Burkitt's-like lymphoma.

Cytogenetic analyses were carried out in a young Haitian immigrant with acquired immunodeficiency syndrome and concomitant Burkitt's-like lymphoma associated with massive bone marrow infiltration. A characteristic 14q+ abnormality was found in all bone marrow cells examined. Although chromosome abnormality involving band 8q24 was not evident in all the cells examined, some karyotypes show that the typical t(8;14)(q24;q32) is most probably present. No other complex rearrangements could be identified. This is the first report of concomitant acquired immunodeficiency syndrome and Burkitt's-like lymphoma in the Haitian community. Our cytogenetic findings provide further evidence for the role of specific chromosomal rearrangements in Burkitt's-like lymphoma oncogenesis in the setting of acquired immunodeficiency syndrome.

Lymphoid interstitial pneumonia after allogeneic bone marrow transplantation. A possible manifestation of chronic graft-versus-host disease.

Interstitial pneumonia (IP) is a frequent and serious complication of bone marrow transplantation with a median time of onset about 2 months posttransplant. Most cases result either from toxicity of radiation and chemotherapy or from infection with pathogens such as cytomegalovirus. Described are two patients with chronic graft-versus-host disease (GVHD) who presented with late-onset IP 242 and 632 days posttransplant. Histologic examination of lung biopsy specimens disclosed a lymphoid interstitial pneumonia (LIP) in both cases. The major lymphocyte subset found in bronchoalveolar lavages and lung tissue was OKT8(+) and showed a positive dot staining for acid phosphatase. Contrary to peripheral blood mononuclear cells, most OKT8(+) lymphocytes in the lungs were OKT3(-). Since acute GVHD lesions are mediated mainly by cytotoxic T-lymphocytes, our data suggest that LIP in marrow-grafted patients may be a manifestation of chronic GVHD. It should be distinguished from the more common types of IP encountered following bone marrow transplantation.

Acute graft-versus-host disease after allogeneic bone marrow transplantation.

In 25 patients receiving allogeneic bone marrow transplants methotrexate was used to prevent acute graft-versus-host disease (GVHD). Acute GVHD, grades 2 to 4, developed in only 5 (20%) of the patients. The incidence of acute GVHD in other series of recipients of bone marrow transplants has ranged from 5% to 76%. A review of the literature suggests that this variation cannot be completely accounted for by age, type of disease treated by transplantation or type of GVHD prophylaxis. However, transfusion of allogeneic lymphocytes that have not been completely inactivated by irradiation (e.g., in platelet and granulocyte preparations) and inadequate isolation-decontamination procedures may increase the probability of GVHD following bone marrow transplantation.