We demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage-CSF (M-CSF) stimulate the differentiation of CD14⁺ human monocytes into two phenotypically distinct types of macrophages, based on morphorogy, cell surface antigen expression and functions including phagocytosis, production of reactive oxygen intermediate, antigen presenting activity and sensitivity to HIV infection. In vivo, however, not only CSF but also many other cytokines are produced under various conditions, and those cytokines may modulate the differentiation of monocytes by CSFs. We demonstrated that CD14⁺ human monocytes can differentiate into CD1⁺ re1B⁺ dendritic cells (DC) by combination of GM-CSF plus interleukin-4 (IL-4), and that they differentiate into tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like multinucleated giant cells (MGC) by combination of M-CSF plus IL-4. However, the monocyte-derived DC were not terminally differentiated cells; they could still convert to macrophages in response to M-CSF. Tumor necrosis factor-α (TNF-α) stimulated the terminal differentiation of the DC by down-regulating the expression of the M-CSF receptor, c-fms mRNA and aborting the potential to convert to macrophages. Taken together, these results provide a new aspect to our knowledge of monocyte differentiation, providing evidence that human monocytes are flexible in their differentiation potential, and that they are precursors not only of macrophages but also of CD1⁺ re1B⁺ DC and TRAP-positive MGC. Such a diverse pathway of monocyte differentiation may constitute one of the basic mechanisms of immune regulation.

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Granulomatous inflammation is the dominant histopathologic feature of cryptococcal infection. Intravenous inoculation of encapsulated Cryptococcus neoformans cells produces granulomas in the rat liver, spleen and lung, where the granulomas play a crucial role in containment and clearance of Cryptococcus cells. In these sites the resident macrophages were the major cell type composed of the granuloma, while the monocyte-derived macrophages predominated in the intravascular granulomas. Enhanced expression of ICAM-1 on the surface of endothelial cells was likely to mediate the formation of intravascular granulomas in the process of disseminated infection. In the CNS an induced expression of class II MHC and CD11b/c antigens was observed as the earliest indication of microglial activation, which preferentially occurred in the white matter. Granuloma macrophages also expressed both these immunophenotypes, although no microglial activation was seen in the vicinity of granulomas in the grey matter. The granulomas in the CNS, however, appeared less effective for clearance of cryptococcal infection because the persistent infection remained even after the extracerebral lesions had totally disappeared. Monocyte-derived, rather than brain-derived, macrophages are believed to be the principal cell population in generating the granulomatous reactions against Cryptococcus cells.

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Recently not only neutrophils but also macrophages have been recognized to have important roles in the host defense mechanism against deep-seated infection of Candida albicans. Activated macrophages can kill Candida cells and inhibit their growth. Macrophages act as both effector cells against Candida albicans and regulator cells which enhance antiCandida activity of other effector cells such as neutrophils through cytokine production. Therefore, Immunological manipulation of the macrophage function seems to make it possible to augment the host defense mechanism against candidiasis. As a typical example, the therapeutic effects of a traditional medicine, Juzen-taiho-to against experimental fungal infection in mice and its mechanism are discussed.

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A murine pulmonary infection model utilizing intratracheal inoculation of high or low virulent strain of Cryptococcus neoformans was used to analyse cytokine production in bronchoalveolar lavage fluid. Lung colony-forming units were increased in the highly virulent strain, while they remained unchanged in the low virulent strain during the 10-day study. Interleukin (IL)-2 and IL-4 were increased in both strains by day 7 after inoculation, and IL-2 in the former strain or IL-4 in the latter strain was declined at day 10. This indicates that Th 1 immune response may play a key role in resistance to the organism.
T cell mitogen concanavalin A-stimulated macrophages and lymphocytes obtained from patients with pulmonary cryptococcosis resulted in release of a high level of IL-10, leading C. neoformans proliferation in the lung through IL-10-induced suppression of alveolar macrophage activation. However, since IL-2 and IL-4 were either comparable or undetectable in this assay, we were unable to define the role of Th 1 or Th 2 cells in patients with pulmonary cryptococcosis. Further investigation will be necessary to determine their roles.

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Host defense against infection with Cryptococcus neoformans is mediated by cellular immunity and macrophages play a central role in the elimination of organisms. To acquire effective microbicidal activity, macrophages need to be stimulated by interferon (IFN)-γ, which is produced by NK cells, γδ cells and helper T cells.
There are two major systems, reactive oxygen and nitrogen reactive intermediates, in the macrophage killing of microbial pathogens. This review focuses on the roles of these mediators in cryptococcocidal activity of macrophages and compares mouse and human macrophages by describing our experimental results.

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Seventy-six clinical isolates of dermatophytes and 8 preserved strains of Arthroderma were investigated by random amplification of polymorphic DNA (RAPD) assay to determine the DNA types of common dermatophytes and find any relationships of DNA-based typing with morphology, teleomorphs, geographic origins and sites of human infection. It was found that each species showed a distinct DNA pattern, which can be used as an identification marker. Forty-two isolates of Trichophyton mentagrophytes were classified into 3 main types and intratype polymorphism was revealed with some primers. No simple relationship was found between DNA type and morphology, but the DNA types of strains were closely related to their geographic origins. The RAPD groups of Arthroderma benhamiae, A. vanbreuseghemii, A. gypsea and A. otae were distinctly different, whereas the 42 clinical isolates of T. mentagrophytes shared similar patterns with A. vanbreuseghemii. Among 30 clinical isolates of T. rubrum, 22 showed almost identical RAPD type, while the other 8 strains differed slightly in band patterns. T. rubrum exhibited great differences from A. benhamiae and A. vanbreuseghemii. In conclusion, RAPD provides a stable and reliable means of typing common dermatophytes, and is a powerful tool for dermatophyte identification and epidemiological study.

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We report two cases of dermatophytosis due to Trichophyton mentagrophytes.
Case 1: At the end of February 1996 a 28-year-old housewife developed erythematous itchy plaques on her chest. On March 5 she visited our hospital for this problem and exhibited pustules and papules. She had two pet rabbits inside of her house. In early January, one of the rabbits developed alopecia, and soon the other developed similar lesions. A veterinarian diagnosed the probrem as fungal infection and used antifungal drugs for treatment. We were unable to isolate any fungus from the rabbits, however, the veterinarian had cultured the rabbit's fur on Sabouraud's dextrose agar. The isolated fungus was identified in our laboratory as Trichophyton mentagrophytes.
Case 2: At the end of August a 3-year-old boy developed erythematous plaques on his back and face which were treated with antifungal cream at a dermatological clinic as tinea corporis, and improvement was excellent. However, at the end of September, he developed scaly lesions in the occipital region with repidly developing alopecia. On September 14 he visited our hospital for this alopecia with numerous crusts and pustules.
In both cases, fungal infections were confirmed by direct examination of the scales or hairs using a KOH preparation. Organisms isolated from these lesions were identified as Trichophyton mentagrophytes. Mating experiment with Arthroderma vanbreuseghemii revealed that the strain from case 2 belonged to (-) mating type.

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Direct examination of Candida albicans and its isolation from the tongues of generally healthy patients with skin disease was done. When a few hyphal fungal elements were detected by KOH method, the direct examination was determined to be positive. The positive rate by KOH method differed with age; there was no positive case in 162 patients under 60 years, however, at 61 years and above the positive rate was 12 of 161 (7.5%). Clinical features of the positive cases were as follows: 7 cases with smooth red tongue, 4 cases with white yellowish plaques on normal-looking tongue, and 1 case with black hairy tongue. Cultures were taken by cotton swab from the tongues of all patients. C. albicans was isolated from 87 of 161 (54.0%) patients 61 years and above, and 16 of 162 (9.9%) under 60 years.
Both the positive rate of direct examination and the isolation of C. albicans of those 61 years and above were thus much higher than those of individuals 60 years and under, and C. albicans was much greater on the tongues of many aged healthy people.

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