Immune response recovery from infection

Undoubtedly, both cellular and humoral immune responses are important to recovery from smallpox. The inability of poxviruses to persist stably within the host cell accounts for their infections being relatively short-lived, without establishment of a latent infection. The importance of cellular immunity in recovery from infection has been demonstrated with other poxviruses,39 and the same is generally assumed with variola. Vaccination experiences demonstrated the rare but terrible consequence of vaccinia necrosum in persons with defects of cellular immunity. Early presentation on the host cell membrane of virus-encoded proteins provides means for immune recognition.40 It has been demonstrated that both antibody-dependent cellular cytotoxicity41 and heterogeneous cluster of differentiation (CD) 4+ cytotoxic T-lymphocyte clones42 are induced in response to vaccinia infection, and some immunodominant B-cell epitopes have been defined in both mice and vaccinated humans.43 The relatively large size of poxvirus polypeptides facilitates their rec-... 

An important distinction must be made between the humoral response to a pure, capsular polysaccharide, and to the same polysaccharide when it is an integral part of the bacterium. Thus, the immunity received on recovery from infection by encapsulated bacteria, in terms of the polysaccharide antigen, differs from that generated by purposeful immunization with purified capsular-polysaccharide vaccines. Fortunately, with the exception of infants, the polysaccharide vaccines still stimulate protective-antibody levels in humans, despite these differences. In infants, due to the immature nature of their immune systems, these polysaccharide vaccines are of only marginal benefit.7 Some insights into the nature of these different responses in humans can be found in studies on the cellular basis of the immune response to polysaccharides. However, for the purposes of this Chapter, it would be inappropriate to provide a lengthy description of this incompletely understood mechanism in-depth reviews of this burgeoning field of research can be referred to.144-147,162-166... 

HBV is not directly cytopathic instead liver injury is immune related, and T lymphocytes are important for both the host cellular and humoral responses. Recovery from acute HBV infection depends on both B-cell and T-ceU responses. B-cell-dependent antibodies are produced to presurface and surface antigens. Cytotoxic T lymphocyte response is mounted against multiple epitopes in the HBV envelope, nucleocapsid, and polymerase regions. Cytotoxic T lymphocyte-mediated lysis of infected hepatic cells occurs, resulting in liver injury. Immune clearance of virus is often accompanied by worsening liver disease, known as a flare. An extreme example of this is seen in fulminant hepatitis B, when there is often no evidence... 

Additionally, it is recognized that HBV is not directly cytopathic, and immune mechanisms are important in both the persistence of, and recovery from, infection. Infection with HBV becomes chronic when a patient fails to clear the viremia within the first six months and the infected hepatocytes are not eradicated by cytotoxic T cells (141). Therefore, early treatment of chronic hepatitis B has been attempted as follows (a) modulation of immune response (by suppression or stimulation), (b) inhibition of viral replication, (c) liver transplant with or without... 

Persons who recovered from smallpox possessed long-lasting immunity, although a second attack could occur in 1 in 1,000 persons after an intervening period of 15 to 20 years.77 As discussed earlier, both humoral and cellular responses are important components of recovery from infection. Neutralizing antibodies peak 2 to 3 weeks following onset, and last longer than 5 years.78... 

Benzene also affects functional immune responses, as indicated by decreased resistance to infectious agents. Pre-exposure to benzene at >30 ppm for 5-12 days increased the bacterial counts in mice on day 4 of infection with Listeria monocytogenes (Rosenthal and Snyder 1985). Recovery of the immune system was noted on day 7. The effects did not occur at 10 ppm. In addition, a concentration-dependent statistically significant depression was noted in T- and B-lymphocyte populations from day 1 through day 7 at 30 ppm and above. B-cells were more sensitive to benzene than were T-cells on a percentage-of-control basis. This indicates a benzene-induced delay in immune response to L. monocytogenes. Concentrations of 200 or 400 ppm for 4-5 weeks (5 days per week) suppressed the primary antibody response to tetanus toxin in mice, but there was no effect at 50 ppm (Stoner et al. 1981). In another intermediate-duration exposure study, no changes were noted in the numbers of splenic B-cells, T-cells, or... 

Recovery from leishmaniasis is thought to depend on the induction of Thl type immune responses and the production of a suite of pro- inflammatory cytokines. However, the picture emerging from the study of the human response to infection is not as clear as that described for some mouse models of disease, where the induction of Thl immune responses is necessary and sufficient for resistance to infection. ... 

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