Protection against pulmonary blastomycosis: correlation with cellular and humoral immunity in mice after subcutaneous nonlethal infection

Abstract

A model of pulmonary blastomycosis in the mouse, in which the portal of entry is the same as natural human infection, was used to study resistance to challenge after subcutaneous infection. One week after subcutaneous infection, mice were partially resistant to pulmonary challenge, and mice challenged two weeks after infection were resistant. Measurement of cellular and humoral immune responses to Blastomyces dermatitidis antigens after subcutaneous infection showed the following. (i) Delayed-type hypersensitivity appeared 1 week after infection, and responses increased for 3 weeks thereafter. (ii) Proliferative responses in vitro appeared in spleen cells at 1 week and in contralateral lymph node cells at 3 weeks, (iii) Serum antibody, detected by an enzyme-linked immunosorbent assay, appeared 1 week after infection and then increased in titer. (iv) Peritoneal macrophages were activated to inhibit replication of B. dermatitidis in vitro by the first week after infection. Prior subcutaneous infection also resulted in rapid clearing of a second subcutaneous challenge, as well as resistance to a lethal intraperitoneal challenge. This resistance was associated with the development of cell-mediated and humoral immune responses. These data provide a chronological framework for selective transfer experiments.

Activation of murine polymorphonuclear neutrophils for fungicidal activity with supernatants from antigen-stimulated immune spleen cell cultures

“…2). These findings are consistent with previous work (22) which showed that peak immunological responses (antigen-induced blastogenesis and delayed hypersensitivity reactions) were optimal 4 weeks postimmunization and then declined. They also suggest that PMN could be activated 24 h after immunized mice were challenged with this pathogen and consequently play a major role in the resistance of mice to reinfection.…”

“…The conditions necessary for the production of active supernatants by antigen stimulation of sensitized spleen cells correlated with those optimal for proliferative responses reported previously (22), e.g., 4 to 6 days in culture. In contrast, supernatants with macrophage activating factor have been generated by antigen stimulation of sensitized human peripheral blood mononuclear cells (2) or murine spleen cells (4, 10) over shorter culture periods, e.g., 2 or 3 days.…”

“…As reported previously (22), resolution of this infection over a period of 4 weeks rendered mice resistant to fatal pulmonary challenge. Resistance correlated with lymphocyte proliferative responses, specific serum antibodies, and cutaneous delayed hypersensitivity reactions to B. dermatitidis antigens (22). Such mice are referred to as immune mice and were used in experiments 4 weeks postinfection.…”

“…Supernatants. Spleen cells were harvested from normal or immune mice and cultured as previously described (22). Briefly, 10 x 106 or 20 x 106 spleen cells per ml of CTCM were stimulated with 0, 100, 200, or 500 ,ug of killed B. dermatitidis cells (whole killed cells [WKC]) per ml in 24well tissue culture plates, 2 ml per well (Falcon no.…”

The Regulation of Pulmonary Immunity

“…Lung infections with two microorganisms, Mtb and Cryptococcus neoformans (Cne), are discussed in this section as examples of infections requiring intact CMI for resolution. Animal models of chronic lung infections with several other important pathogenic organisms have been studied, including Pneumocystis carinii (Walzer, 1984;Shel-lit0 et al, 1990;Harmsen and Stankiewicz, 1990;Boylan and Current, 1992), Histoplasma capsdatum (Baughman et al, 1986;Defaveri and Graybill, 1991;Fojtasek et al, 1993;Allendoerfer et al, 1993), Blastomyces dermitiditis (Morozumi et al, 1982;Moser et al, 1988;Frey et al, 1989;Williams et al, 1994), Paracoccidiodes braziliensis (Brummer et al, 1984;Defaveri et al, 1989), Coccidiodes immitis (Cox et al, 1988), Chlamydia trachomatis and psittaci (Williams et al, 1988), Rhodococcus equi (Kanaly et al, 1993), and Mycobacterium auiumintracellulare (Takashima and Collins, 1988). Although infection with Legionella pneumophila can cause an acute pneumonia in susceptible hosts, it is a facultative intracellular bacterium; CMI is thought to be necessary for resolution of the infection.…”