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The functional and morphological effects of cyclophosphamide (Cy) on the immune response of the chicken were investigated. Chickens given Cy on days 1, 2 and 4 after hatching failed to produce antibody for at least 6 weeks and had low levels of serum IgG. Birds surviving for more than 6 weeks recovered their immunocompetence. The effect of Cy on cell-mediated immunity (CMI) was less persistent. Allogeneic skin grafts applied to one-week-old treated birds were not rejected but grafts versus host activity completely eliminated by Cy treatment. Morphological changes in the lymphoid organs reflected the results of functional tests. Early after treatment, lymphocytes were eliminated from thymus bursa and spleen. Lymphoid regeneration was observed less frequently, and usually only in birds older than 6 weeks. In many birds, chronic degenerative changes in the epithelial cells were apparent, especially in the bursa. It was speculated that in those birds where thymus or bursa regeneration failed to occur there was damage to the epithelial component of the organs. Possibly the bursal epithelial cells were more susceptible to the action of Cy than were thymic epithelial cells. [ABSTRACT FROM AUTHOR]

Cholera toxin (CT) is a strong systemic and mucosal adjuvant that greatly enhances IgG and IgA immune responses, but its adjuvant effects for cellular immunity, particularly class I-restricted cytotoxic T lymphocyte (CTL) responses, are less well understood. In the present report, CT and the purified non-toxic B component (CTB) were assessed for their ability to facilitate class I-restricted CTL induction to soluble proteins as well as to permit sensitization of target cells for CTL-mediated lysis. Priming for ovalbumin (OVA)-specific CTL occurred following oral exposure to a combination of OVA with CT plus CTB. In addition, CTB mixed with soluble proteins and administered intravenously primed mice for antigen-specific class l-restricted CTL. Target cells could also be sensitized for CTL-mediated killing following their exposure to soluble antigen and CTB in vitro. These results indicate that combinations of CT and CTB not only enhance antibody responses, but also have an immunomodulating effect to allow sensitization and priming for antigen-specific class lrestricted CTL. [ABSTRACT FROM AUTHOR]

In humans CD4+ major histocompatibility complex (MHC) class II-restricted T cells dominate cytotoxic T-lymphocyte (CTL) responses to herpes simplex virus (HSV), whereas in the mouse only CD8+ MHC class I-restricted CTL have been reported. In this study, we demonstrate that a minor fraction (around 30%) of the response in draining lymph nodes of acute local HSV infections is attributable to CD4+ CTL mice. Such CTL were identified on the basis of antiserum inhibition studies, negative depletion approaches, as well as their differing antigen processing requirements to CD8+ MHC class I-restricted CTL. A possible role for CD4+ CTL as immunoregulators in local infections is discussed briefly. [ABSTRACT FROM AUTHOR]