Prevalence and pattern of cross-reacting antibodies to HIV in patients with tuberculosis.

In many countries, HIV testing among tuberculosis (TB) patients is recommended so that both infections are appropriately treated. Cross-reacting antibodies to HIV antigens have been reported for several conditions, including TB, leprosy, malaria, and rheumatoid arthritis. To study the pattern and prevalence of cross-reacting antibodies to HIV antigens, we examined sera from 153 HIV-negative TB patients and 40 healthy individuals in Chennai, south India. We also studied the differences in cross-reactivity of various HIV antigens using two different Western blot kits. Of the 153 samples studied, 80 were tested using HIV Western blot and 73 were tested using INNOLIA. Most patients in the study had concordantly negative ELISA and rapid tests, and no subject had a positive Western blot. However, seven TB patients had antibodies that cross-reacted with HIV antigens, giving rise to an indeterminate result. While p51/55 was the most frequently recognized antigen in the Western blot assay, antibodies to sgp120 was most frequently identified in INNOLIA. Sequence similarities between the two organisms could be responsible for eliciting cross-reacting antibodies, since a few related epitopes were identified in HIV and Mycobacterium. These findings could have potential implications for the development of diagnostics and vaccines.

Immunity, immunopathology and vaccines against HIV?

Immunity and immunopathology of HIV infections leading to AIDS are reviewed from an evolutionary point of view. Accordingly infectious agents and host defences have co-evolved to reach balanced states where virus and host survive. While HIV has not quite yet reached an optimal balance, tuberculosis (TB), leprosy, HBV, HCV in humans or lymphocytic choriomeningitis virus (LCMV) in mice have successfully established persistence. These non- or poorly-cytopathic infections infect the next host usually before or at birth while hosts are immunoincompetent. They also infect immunocompetent hosts to persist at low levels concomitant with an ongoing T and B cell immune response that is repeatedly triggered by latent or persistent infection of extralymphatic or lymphatic host cells. This infectious or infection-immunity is the basis for cellular immunoprotection by antigen activated T cells. Because we cannot imitate this infection-immunity long-term and cannot build polyspecific vaccine combinations covering all possible neutralising variants yet, vaccines against TB, leprosy, HCV and HIV only protect transiently and incompletely.

Zinc-controlled Th1/Th2 switch significantly determines development of diseases.

Functional, excessive-possibly temporary-deficiencies of the trace element zinc can change immune functions prematurely from predominantly cellular Th1 responses to humoral Th2 responses. T helper (Th1) cells produce cytokines such as interleukin-2 (IL-2) and interferon gamma, thereby controlling viral infections and other intracellular pathogens more effectively than Th2 responses through cytokines such as IL-4, IL-5, IL-6 and IL-10. The accelerated shift from the production of extra Th1 cells during these cellular immune activities to more Th2 cells with their predominantly humoral immune functions, caused by such a zinc deficiency, adversely influences the course of diseases such as leprosy, schistosomiasis, leishmaniasis and AIDS, and can result in allergies. It is noteworthy that AIDS viruses (HIVs) do not replicate in Th1 cells, which probably contain more zinc, but preferentially in the Th0 and Th2 cells; all the more so, because zinc and copper ions are known to inhibit intracellular HIV replication. Considering the above Th1/Th2 switch, real prospects seem to be offered of vaccination against such parasites as Leishmania and against HIVs.

O estudo da resposta imune em pacientes com infecçäo pelo vírus da imunodeficiência humana (HIV) em relaçäo ao antígeno de Mitsuda / The study of immune reponse in patients with infection by HIV in relation to Mitsuda's pathogen

Os autores apresentam resultados de estudo da resistência à infecçäo hansênica em 22 pacientes HIV positivos do Hospital Universitário Clementino Fraga Filho, da Universidade Federal do Rio de Janeiro, mediado pela correlaçäo clínico-patológica do Teste de Mtsuda e outros parâmetros. A amostragem evidenciou 77% de reaçöes negativas, 13% duvidosas e 9% positivas. A observaçäo histológica da reaçäo de Mitsuda mostrou granuloma tuberculóide em nove pacientes (40%) em diferentes fases de formaçäo, permitindo aos autores concluir que a infecçäo pelo HIV diminui sensivelmente, de forma lenta e graudal, a capacidade dos indivíduos de formarem granuloma tuberculóde e de lisar Baar, jogando-os para uma faixa de menor reatividade defensiva constitucional, mais próxima do pólo virchowiano. Atribuem a disfunçäo básica a alteraçöes do linfócito T colaborador e seus subprodutos, principalmente a interleucina II e o interferon