The relative susceptibility of New Zealand black and CBA mice to infection with opportunistic fungal pathogens

The susceptibility of ageing New Zealand Black (NZB) mice to infection with a number of opportunistic fungi and yeasts wsd compared with that of similarly aged mice of the CBA strain. The NZB mice showed a greater susceptibility to lethal infection with Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans than did those of the CBA strain. Both mouse strains showed similar susceptibility to lethal infection by Allescheria boydii, Absidia corymbifera, Mucor pusillus and Rhizopus oryzae. The clinical and histopathological characteristics of the infections produced by Allesch boydii, Asp. fumigatus, Abs. corymbifera, M. pusillus and R. oryzae were similar for both mouse strains. In contrast C. albicans and Crypto. neoformans produced much more severe infections in NZB mice than in CBA mice. These results suggested that T-lymphocyte dependent immune processes played a major role in resistance to C. albicans and Crypto. neoformans but not to Abs. corymbifera, Allesch. boydii, Asp. fumigatus, M. pusillus or R. oryzae.

Suppressor thymus-derived lymphocytes in fungal infection

Thymus-derived lymphocyte (T-cell) function, as determined in vivo by cutaneous reactivity to several antigens and in vitro by responsiveness to mitogens and antigens, was assessed in 14 patients infected with a variety of fungal organisms. While all patients manifested a normal frequency of peripheral blood T cells, only seven patients reacted to at least one of the antigens used for cutaneous testing and demonstrated normal in vitro T proliferative responses. Three patients exhibited cutaneous anergy but normal in vitro T-cell reactivity while four patients demonstrated persistent anergy and marked in vitro T-cell hyporeactivity which was independent of activity of infection, concurrent medication, or any associated disorders. The marked diminution of in vitro T-cell reactivity noted for these later four patients was not due to a deletion of antigen- or mitogen-reactive cells. Thus, patients' cells which had been initially cultured for 7 days without any mitogenic or antigenic stimulus and which were subsequently washed and recultured with phytohemagglutinin, concanavalin A, or histoplasmin demonstrated a marked increase in their responsiveness. Moreover, this reactivity noted for recultured cells could be suppressed by a nonphagocytic, nonadherent, nonimmunoglobulin-bearing, sheep red blood cell rosette-forming population of cells isolated from the fresh peripheral blood mononuclear cells of the same patient. While these "regulator" T cells were capable of suppressing T-proliferative responses to antigens and mitogens, they did not diminish pokeweed mitogen-induced immunoglobulin synthesis by normal bone marrow-derived lymphocytes. Patients in whom suppressor "T" cells were found were at risk for relapsing, disseminated fungal infection.

Laboratory diagnosis of parasitic and fungal diseases of the central nervous system

This review is presented to bring attention to those fungal and parasitic organisms that have been associated with central nervous system (CNS) infection and to offer an approach for handling their laboratory diagnosis. Treatment of the cerebrospinal fluid (CSF) to yeild best results on direct smear examination and culture are discussed. Culture procedures and staining methods to be done are given in chart form. Those immunologic tests useful in supporting the diagnosis of fungal or parasitic CNS infections are also included.

Invasive fungal infection in the immunosuppressed host

Immunosuppression, whether arising as a consequence of disease (haematopoietic and lymphoreticular malignancies) or therapy (against hemograft rejection or malignancy results in a higher than normal incidence of invasive fungal infections such as candidiasis, aspergillosis, mucormycosis and cryptococcosis. Normal host defense mechanisms, both immunologic and non-immunologic, are not fully functional and may contribute to the pathogenesis of these diseases.Candida, normally a superficial colonizer, may invade the gastrointestinal, respiratory or urinary tracts. Aspergillus and mucor species may cause hemorrhagic or necrotising pneumonias and secondarily spread to the brain. Cryptococcus may infect the meninges in the appropriate host. Therapeutics for these diseases is limited. Amphotericin B may alter the course of any of the four diseases. Fluorocystosine has found some use in the treatment of candidiasis and cryptococcosis.

Infections in the immunosuppressed patient

Infections in the immunosuppressed cancer patient are caused by a wide variety of bacteria, viruses, fungi, and protozoa; many of these in the normal individual are saprophytes but will cause disease in the immunosuppressed patient, often with treatment failure. Patterns of infection are recognized, and this should enable the physician to plan a meaningful course of action when infection occurs in the compromised host. Obviously, it would be much better to prevent rather than have to treat infection in these immunosuppressed patients. Ideally, in the future, it is hoped that drugs which have less suppressive effect on defense mechanisms will provide a partial solution to the problem of infection in the immunosuppressed patient.