Tomaz A. Mota-Santos

Identification of SPAM messages using an approach inspired on the immune system.

In this paper, an immune-inspired model, named innate and adaptive artificial immune system (IA-AIS) is proposed and applied to the problem of identification of unsolicited bulk e-mail messages (SPAM). It integrates entities analogous to macrophages, B and T lymphocytes, modeling both the innate and the adaptive immune systems. An implementation of the algorithm was capable of identifying more than 99% of legitimate or SPAM messages in particular parameter configurations. It was compared to an optimized version of the naive Bayes classifier, which has been attained extremely high correct classification rates. It has been concluded that IA-AIS has a greater ability to identify SPAM messages, although the identification of legitimate messages is not as high as that of the implemented naive Bayes classifier.

Towards a novel immune inspired approach to temporal anomaly detection

In this conceptual paper, we report on studies and initial definitions of an immune-inspired approach to temporal anomaly detection problems, where there is a strict temporal ordering on the data, such as intrusion detection and fault detection. The inspiration for the development of this approach comes from the sophisticated mechanisms involved in T-cell based recognition, such as tuning of activation thresholds, receptor down-regulation, among others. Despite relying on low affinity and highly degenerate interactions, the recognition of foreign patterns by T cells is both highly sensitive and specific. Through a proper understanding of some of these mechanisms, this work aims at developing an efficient computational model using some of these concepts.

Schistosoma mansoni: phospholipid methylation and the escape of schistosomula from in vitro cytotoxic reaction

The ability of Schistosoma mansoni schistosomula to evade in vitro cytotoxic activity of antibodies plus complement is shown to be increased by incubation with Concanavalin A (Con A) or with non-immune inactivated human serum. This effect was not observed if S-adenosyl-homocysteine (SAH) a methyltransferase inhibitor was added to the incubation medium. Methyl group incorporation occurs in schistosomulum phospholipids if parasites are incubated in Earles balanced salt solution. This incorporation is increased by Con A addition and this increase is inhibited by SAH. Supernatants of schistosomula incubated in culture media containing Con A were able to promote phospholipid methylation, showing that methyltransferases were liberated into the culture media. The possible roles played by these phenomena in host-parasite interactions are discussed.

A novel immune inspired approach to fault detection

This paper presents a novel immune inspired algorithm, named DERA (Dynamic Effector Regulatory Algorithm), aimed at fault detection and other anomaly detection problems. It integrates immunological research results, pointing out the importance of a special breed of cells (regulatory T cells) in the control of various aspects of the immune system, and includes a mechanism for signalling between cells. Preliminary results of the application of the proposed model to the DAMADICS fault detection dataset are presented, indicating that the proposed approach can attain good results when properly tuned.

Schistosoma mansoni: experimental infection of mice through the ear and estimation of skin parasitism

A method is presented to recover schistosomula from the skin of ear infected mice. About 80% of the cercariae applied to the ear were able to penetrate the mouse skin and 30% of them were recovered from the portal system as adult worms. The best recovery of larvae from the ear occurred in the two days that follow the penetration. From the 3rd day on, parasites were recovered both from skin and lungs and on the 4th day they were already found mainly in the lungs. From 73 to 80% of the parasites eventually found in the portal system can be recovered as schistosomula from the skin on tjhe 2nd day of infection. The use of the mouse ears is suggested for the parasitolqgical analysis of the initial events of the S. mansoni infection both in normal and in immune animals, for they are very convenient to the cercarial access and to the use of methods of study of migration and recuperation of the larvae.No presente trabalho, desenvolveu-se metodo de infeccao de camundongos atraves da orelha e de recuperacao de esquistossomulos resultantes dessas infeccoes. Cerca de 80% das cercarias postas em contacto com orelhas de camundongos penetraram. Destas, 30% foram recuperadas. como vermes adultos, do sistema porta. Da pele (das orelhas) as maiores recuperacoes de esquistossomulos ocorreram nos dois primeiros dias apos a infeccao. Os parasitas permaneceram nesse sitio por dois dias. No terceiro dia, os parasitas foram recuperados tanto da pele como dos pulmoes. A partir do 4.° dia, foi predominante a recuperacao de esquistossomulos ao nivel dos pulmoes. Do total de parasitas que potencialmente atingiriam o sistema porta, proporcao elevada (73-80%) pode ser recuperada da pele, no segundo dia apos a infeccao, como esquistossomulos. Revelando-se apropriadas ao acesso, a migracao no hospedeiro e as tecnicas de recuperacao de parasitas, sugere-se que orelhas de camundongos podem ser utilizadas como sitio de infeccao para estudos que visem a analise parasitologica dos eventos iniciais da infeccao em animais normais ou imunes.

Regulatory T cells: inspiration for artificial immune systems

In this conceptual paper, some features of regulatory T cells are described. These cells have been receiving an increasing attention in Immunological research, due to their importance in several aspects of the immune system. As will be argued, these cells constitute an important source of inspiration for developing Artificial Immune Systems, computational tools that attempt to capture some of the characteristics of the natural immune system. It is expected that the incorporation of these cells in some immune inspired algorithms may not only lead to more biologically plausible models, but also to algorithms that can achieve better results in real-life problems.

Anaphylaxis with Schistosoma mansoni extracts in normal and infected mice

Methods generally utilized for studies on anaphylaxis to protein antigens such as determination of histamine release to the blood, hemoconcentration, histamine release from peritoneal mast cells and passive cutaneous anaphylaxis (PCA) were used to investigate some aspects of the anaphylaxis to parasite antigens in Schistosoma mansoni infected mice. The release of histamine to the blood and significant rates of hemoconcentration were induced by intravenous injection of schistosomula or cercarial extracts into 10-13 weeks infected mice. Cercarial, schistosomula, worm tegument and soluble egg antigens were able to trigger histamine release from peritoneal mast cells from chronically infected mice. In spite of the PCA reaction beeing detected within 2 hours of sensitization (IgG1antibodies) in 6 of 8 tested sera from chronically infected mice, no detectable reactions were obtained after 48 hours sensitization (IgE antibodies). Although IgE was not detected in the circulation, by the PCA technique, the results indicate that the infected mice contained IgE antibodies bound to their mast cells.

On the Relevance of Cellular Signaling Pathways for Immune-Inspired Algorithms

In this conceptual paper, we discuss the relevance of cellularsignaling pathways for immune-inspired algorithms. With complexdynamics, the mapping of environment stimuli to cellular responsesis highlighted as a decision making capability. When consideringapplications which could benefit from these dynamics, thepossibility of incorporating these pathways can be an interestingway to combine more biologically-plausible algorithms and improvedperformance. The structure of the NF-κB (NuclearFactor κB) and MAP (Mitogen-activated protein)kinases pathways, and the pathways involved in signaling byToll-like receptors, are presented. As an example, we then considerhow these pathways could be incorporated in the Dendritic CellAlgorithm.

[Schistosoma mansoni: cutaneous resistance in mice with primary infection].

Evaluation of the cutaneous resistance of mice to Schistosoma mansoni -was performed using the pinna of the ear as the site of infec-tion and recovery of schistosomules by incuba ting the ear fragments in Hepes-buffered. Elac medium. This method was found to be effective for counts of recovered schistosomules in normal and previously infected (immune) mice when compared with the technique of skin digestion in a collagenase containing medium. A decrease of 42% to 46% of the parasitism was shown to occur in immune mice from days 1 to 7. This resistance was observed in mice with bisexual (6-15 weeks) and unisexual (33-34 weeks) infections, as well as in inbred (C57 BL/IO, CBA and F, from CBA x CBA2 crossing) and outbred Swiss animals. Since the pinna of the ear proved to be very useful in the study of antischistosomotic resistance in mice, at skin level, it is suggested that it should be utilized as standard infection route to study the factors affecting the immunity to S. mansoni in mice.