IMMUNOLOGICAL ACTIVITIES OF A CANDIDA-ALBICANS PROTEIN WHICH PLAYS ANIMPORTANT ROLE IN THE SURVIVAL OF THE MICROORGANISM IN THE HOST

A protein with an isoelectric point of 4.3 and a relative molecular ma ss of 43 kDa (p43) was purified from the supernatants of the cultures of pathogenic Candida albicans but could not be detected in the supern atants of cultures of this fungus with pathogenicity previously attenu ated after being repeatedly subcultured in vitro. Treatment of BALB/c and C57BL/6 mice with p43 resulted in (i) marked increases in the numb ers of splenic immunoglobulin-secreting plaque-forming cells (PFC) wit h peak responses of immunoglobulin M (IgM) PFC preceding those of IgG PFC, with an isotype restriction pattern of IgG2a>IgG2b>IgG3>IgG1>IgM, and (ii) specific immunosuppression of the murine primary immune resp onse against sheep erythrocytes. Immunosuppressive and B-cell mitogeni c properties of p43 were quantitatively associated and inversely corre lated with susceptibility to C. albicans infection. C57BL/6 mice treat ed with p43 2 days before inoculation with C. albicans were considerab ly more susceptible to the fungal infection than untreated mice. The i mmunobiological and chemical properties of p43 are compared with previ ously described immunosuppressive and B-cell mitogenic proteins produc ed by bacteria and viruses, and strategies for immunointervention are discussed.