The authors report an unusual case of fungal keratitis caused by Histoplasma capsulatum in a male immunocompetent patient. PCR confirmed the presence of the fungus DNA in the material studied. To our knowledge this is the first reported case in humans described all over the world.

A imunodeficiência comum variável (CVID) é uma doença caracterizada por hipogamaglobulinemia, infecções recorrentes, especialmente das vias aéreas, enfermidades auto-imunes e neoplasias. Alguns pacientes com CVID possuem diversos distúrbios do sistema imune como alterações no número e proporção de diferentes populações leucocitárias; resposta proliferativa linfocitária diminuída para antígenos e mitógenos; produção alterada de citocinas e alteração na expressão de moléculas de superfície. Neste trabalho, são discutidas várias destas alterações imunológicas procurando correlacioná-las aos achados clínicos dos pacientes e incorporar aos dados da literatura os nossos próprios achados.

Common variable immunodeficiency (CVID) is an immunological disorder characterized by defective antibody production, recurrent infections, most notably of the respiratory tract, autoimmune phenomena and cancer. Some CVID patients may also present disturbances of the cellular immune response such as a decrease in the number and proportion of different lymphocyte populations, diminished lymphoproliferative response to mitogens and antigens, altered production of cytokines, and deficient expression of cell-surface molecules. Most Brazilian CVID patients included in this study show a decrease in T and B lymphocyte counts in the peripheral blood. Furthermore, their lymphocytes are more susceptible to apoptosis following activation than normal individuals, and they have a decrease in the expression of activation molecules like CD25, CD69, CD40L and CD70. Moreover, they show a decreased synthesis of IL-4 and IL-5 in comparison with normal individuals. The increase in susceptibility to apoptosis following activation, may also be responsible for the decrease in the expression of activation molecules and CD40L, decrease in Th2 cytokines synthesis, and in the number of T and B circulating cells. In this study we discuss some of these immunological disturbances correlating them to the patients' clinical features and comparing our patients' findings to the literature.