Histoplasmosis is caused by two varieties of Histoplasma capsulatum (H.c.var capsulatum & H.c. var doboisii). Information related to host defense against H. c. var doboissi isminimal. Histoplasmosis is a mycosis of the reticuloendothelial system involving lungs spleen, kidneys and other organ systems (1,2). Primary infection is acquired by inhalation of microconidia of H. capsulatum . Cases of Histoplasmosis have been reported from every continent . The area of highest incidence are the United States and Latin America. H. capsulatum is well known as a soil inhabitant.The majority of individuals who inhale conidia of this fungus remain free of disease. Those who become ill manifest a primary pulmonary disease (3). H. capsulatum is not a regular opportunist but is known to produce infections in persons who are immunocompromised by malignancies (3,4) and persons with AIDS (5).

High levels of serum antibodies to H. capsulatum are more often observed in patients with progressive Histoplasmosis and serologic detection of antibodies has value in establishing the diagnosis of the disease. Studies have shown that sensitive assays such as EIA can be used for detection of antibodies to H. capsulatum (6). Antibodies directed against H. capsulatum have been demonstrated within the IgM, IgG, and IgA classes (7).