The allergens causing mango dermatitis have long been suspected to be alk(en)yl catechols and/or alk(en)yl resorcinols on the basis of observed cross-sensitivity reactions to mango in patients known to be sensitive to poison ivy and oak (Toxicodendron spp.). Earlier, we reported the 3 resorcinol derivatives: heptadecadienylresorcinol (I), heptadecenylresorcinol (II) and pentadecylresorcinol (III); collectively named 'mangol', as mango allergens. In this study, we extracted the 1st 2 components (I and II) from the Philippine mango, adjusted them to 0.05% concentration in petrolatum and patch tested the components on 2 subjects with mango dermatitis. Both subjects reacted to I. 1 subject also elicited a weaker positive reaction to II. To investigate the cross-reaction between mangol and urushiol, we also patch tested the same subjects with urushiol. The subject sensitive to II reacted to urushiol. 6 subjects with a history of lacquer contact dermatitis and positive reactions to urushiol were similarly patch tested. 5 persons reacted to I. 2 subjects also exhibited a slower but positive reaction to II. This is the 1st report in which heptadec(adi)enyl resorcinols known to be present in mango have been shown to elicit positive patch test reactions in mango-sensitive patients.

To evaluate the mechanism of mosquito bite reaction in man, the reaction to Aedes albopictus was observed in 162 subjects ranging in age between 1 to 68 years old. Bite reactions were found to consist of both an immediate and a delayed reaction. The eruption and time course of the immediate reaction were consistent with type I hypersensitivity. The eruption and time course of the delayed reaction were consistent with cutaneous basophil hypersensitivity. Positive rates of immediate reaction increased from early childhood to adolescence and decreased with age from adulthood. The appearance and intensity of the delayed reaction decreased with age. Mosquito bite reactions in human beings exposed continuously and regularly are known to change from stage 1 to stage 5 (stage 1; no reaction, 2; delayed reaction only, 3; immediate and delayed reaction, 4; immediate reaction only, 5; no reaction). Analysis of the relationship between age and bite reaction in this study indicated that the principle held true even when the exposures were irregular or at random.

To investigate the mechanisms responsible for mosquito bite reaction, 120 subjects were experimentally exposed to Aedes albopictus bite and two types of immunological tests were performed. Specific IgE antibodies to salivary gland extract (SGE) antigens of female Aedes albopictus were measured by enzyme-linked immunosorbent assay (ELISA) in all subjects. Lymphocyte transformation tests (LTTs) to the same antigens were measured in 51 of the 120 subjects. The relationships between the results of ELISA and LTTs with bite reactions were statistically analysed. The amount of specific IgE antibodies correlated well with immediate bite reactions (r = 0.55) (p less than 0.01). Stimulation indices (SIs) to SGE antigens correlated with delayed bite reactions (r = 0.54) (p less than 0.01). The results suggest that type I hypersensitivity plays a role in the immediate reaction to mosquito bites and a cellular immune mechanism is responsible for the pathogenesis of delayed bite reactions.

Eruptive pseudoangiomatosis is a skin eruption characterized by millet-sized erythema with an anemic halo appearing on exposed body areas. Insect bites, particularly mosquito bites, have been reported as one of the causes of eruptive pseudoangiomatosis. We experienced two cases of eruptive pseudoangiomatosis and the eruption was seen on the face and upper extremities of two women aged 48 and 77 years old. The two cases consented to be experimentally bitten by Culex pipiens mosquitoes and Aedes albopictus to determine if eruptive pseudoangiomatosis could be experimentally elicited by these mosquitoes. Our results showed that several minutes after a C. pipiens mosquito bite, an erythematous spot appeared on the bite site, followed by the formation of an anemic halo surrounding the erythema in 30 min; a successful reproduction of eruptive pseudoangiomatosis. The erythema lasted for more than a week and was not accompanied by any pruritus. With A. albopictus, we were able to reproduce a milder eruptive pseudoangiomatosis eruption: in case 1, a smaller erythematous spot with an ill-defined halo which disappeared within 1 week; and in case 2, an immediate response consisting of a wheal and erythema but not eruptive pseudoangiomatosis. We demonstrated that eruptive pseudoangiomatosis was the response manifested in individuals who normally did not demonstrate any immediate or delayed reaction to insect bites; and the typical eruptive pseudoangiomatosis eruption was elicited by C. pipiens mosquito bites. However, the mechanism resulting in the manifestation of eruptive pseudoangiomatosis is still unknown.

A 70-year-old woman who had suffered from aseptic meningitis complained of chronic headache after dental treatment including tooth extraction. She developed a fever and respiratory failure. Based on chest computed tomography and head magnetic resonance imaging (MRI), she was diagnosed with osteomyelitis in the clivus accompanying moderate pituitary involvement, cavernous sinus thrombosis and septic pulmonary embolism. Both of the causal bacteria, Fusobacterium nucleatum and Campylobacter rectus, were isolated from her blood. Dual infection leading to clival osteomyelitis and cavernous sinus thrombosis has not been reported. It is important to perform enhanced MRI and blood culture for patients with chronic headache related to dental treatment.

Dermatitis caused by contact with tentacles of jellyfish was studied on 25 volunteers. Two tentacles cut from a living jellyfish, Carybdea rastonii, were applied on each of the forearms and skin reactions were observed. All volunteers complained of severe pain, which lasted from 10 min to 8 hrs. Erythema and wheal appeared within 3 to 4 min and enlarged for 15 to 20 min. Erythema subsided within 24 hrs to 3 days in all but two individuals. Seven to 13 days after the application, linear erythema and papulo-vesicular lesions with pruritus were observed on the forearms of 15 out of 25 volunteers tested. These flare-up lesions lasted for one week leaving slight pigmentation. Histological findings from the flare-up lesions corresponded to those of allergic contact dermatitis. The lymphocyte response to the jellyfish venom in the subjects who had recurring lesions was greater than that in either the subjects with no recurring lesions or the control group, who was never exposed to jellyfish.

To evaluate the mechanism of mosquito bite reaction in man, salivary gland extracts from female Aedes albopictus were prepared. When the extract of the gland was analysed by ion-exchange high performance liquid chromatography the amount of histamine in a pair of salivary glands of one mosquito was found to be below the limit of detection, an amount which is insufficient to produce an immediate reaction. Salivary gland extracts were fractionated to higher and lower molecular weight components. Intradermal injection tests with salivary gland extracts, which contained less than 100 ng of protein showed that the higher molecular weight fraction (molecular weight greater than 10,000) elicited an immediate and a delayed reaction similar to a bite reaction.

This study was designed with two purposes: first, to elucidate immunologic mechanisms in different cutaneous reactions, particularly in hypersensitivity to mosquito bites, and, second, to develop a more reliable and safer method of identifying the causative species of mosquito in severe cases. The amounts of IgG, IgG4 and IgE specific to the mosquito salivary gland extract of Aedes albopictus were determined in the sera of 116 volunteers with normal reactions, either immediate or delayed, and 4 patients with severe systemic symptoms caused by mosquito bites. Titers of IgG and IgE in the severe cases were considerably higher than in volunteers with normal reactions, but there were no differences in IgG4 titers between the two groups. These results indicate that high titers of IgG and IgE may be involved in development of systemic symptoms in severe cases and verify the possibility of in vitro tests to identify causative species of the mosquito.