Amniotic fluid embolism, anaphylaxis, and tryptase.

It has been recently suggested that amniotic fluid embolism is an anaphylactic reaction to fetal antigens. This hypothesis can be readily tested by obtaining serum tryptase levels within a few hours of the appearance of symptoms in affected patients.

Multi-centre comparison of ABBOTT MATRIX Aero to Pharmacia Standard RAST, Modified RAST and skin puncture tests.

ABBOTT MATRIX Aero is an enzyme immunoassay which measures specific IgE antibodies to 14 individually calibrated airborne allergens using a single serum specimen. In this study, ABBOTT MATRIX performance was evaluated in comparison to the results of skin puncture test and the Standard and Modified RAST procedures. The ABBOTT MATRIX demonstrated overall sensitivity of 89% vs. Standard RAST and Modified RAST, with specificity greater than 92% vs. both methods. ABBOTT MATRIX sensitivity vs. skin test (71%) exceeded that of the Standard and Modified RAST procedures (62% and 67% respectively). Positive results reported by ABBOTT MATRIX but not RAST were corroborated by skin test results for 3 of 5 allergens evaluated. All in vitro systems demonstrated specificity of approximately 90% vs. skin test. The ABBOTT MATRIX system provided results which compared favorably with the results of skin test and RAST, but required less hands-on time to obtain quantitative specific IgE measurements to multiple allergens.

Development of the Abbott MATRIX Aero assay for the measurement of specific IgE.

An enzyme immunoassay has been developed for the quantitation of specific immunoglobulin E (IgE) in human serum to a panel of allergens. The assay system, called the Abbott MATRIX Aero, includes an instrument, reagents and test cell disposables. Each test cell contains fourteen airborne allergens individually localized on a nitrocellulose solid phase. Individual calibration curves for each allergen are established by the manufacturer and included in barcode form with each test kit. Stable factory calibration eliminates the need to establish a calibration curve with each assay run. The instrument automatically incubates, washes, and reads the test cell and prints each result, which ensures assay reproducibility and provides ease-of-use. Analysis of test results shows good agreement with another in vitro assay for specific IgE. The Abbott MATRIX Aero is a sensitive, reproducible and easy-to-use system for the measurement of specific IgE to a panel of fourteen allergens simultaneously using a single, small volume of serum.

Levels of IgE in serum from normal children and allergic children as measured by an enzyme immunoassay.

Serum IgE levels of 346 nonallergic and 301 allergic children were measured by an enzyme immunoassay. The data are presented as the geometric mean +/- 95% confidence interval for each age from less than 1 to 12 years of age with those 13 to 16 years of age, pooled. The geometric mean for nonallergic patients increases from 0.9 IU/ml at less than 1 year of age to 45.4 IU/ml at 13 to 16 years of age. By use of an IgE value between confidence intervals of allergic and nonallergic subjects, a cutoff value for each age was established to differentiate allergic from nonallergic children. This value increases from 10 IU/ml at less than 1 year to 100 IU/ml at 13 to 16 years of age. The diagnostic sensitivity and specificity of the assay, based on the cutoff values, average 83% and 91%, respectively.

Studies of kissing bug-sensitive patients: evidence for the lack of cross-reactivity between Triatoma protracta and Triatoma rubida salivary gland extracts.

In the southern and western sections of the United States, bites from the reduviid bug, commonly known as the kissing bug, genus Triatoma, may induce serious life-threatening allergic reactions. This study was undertaken to identify the allergens responsible for patient sensitization and to determine the extent of cross-reactivity of these allergens. The Triatoma spp. most commonly encountered in California and Arizona, T. protracta and T. rubida, were obtained, maintained in the laboratory, and dissected to prepare extracts for testing. Extracts were prepared from T. protracta and T. rubida for study by RAST, lymphocyte transformation, leukocyte histamine release, and RAST inhibition. Sera and cells were collected from patients who had generalized reactions to Triatoma bites. Our results indicate that T. protracta and T. rubida antigens to which patients are sensitized are present in extracts that contain saliva and that human responses are specific for T. protracta or T. rubida, i.e., allergic cross-reactivity could not be demonstrated.

Deficiency of UV-induced excision repair in human thymocytes.

The capacity of human thymocytes and of differentiated lymphocytes circulating in peripheral blood to perform unscheduled DNA synthesis (a measure of nucleotide excision repair) after UV irradiation was measured by radioautographic analysis. Only 4% of immature T lymphocytes, but 68% of circulating lymphocytes exhibited unscheduled DNA synthesis. When UV sensitivity of peripheral blood lymphocytes and thymocytes from the same donor were compared, the thymocytes, in each case, were significantly more UV sensitive than were the circulating lymphocytes. Peripheral blood lymphocytes from subjects undergoing halothane and morphine anesthesia during surgery showed 56% less excision repair capacity than those from unanesthetized donors. The difference occurred in the number of cells capable of repair rather than in the extent of repair synthesis per cell. Ultraviolet-induced unscheduled DNA synthesis occurred in only 3% of the thymocytes removed from rats killed by cervical dislocation. Therefore, the deficiency of excision repair was observed in rat thymocytes which had not been affected by anesthesia or surgical trauma. Since the thymus contains more than 90% immature T-cells, our results indicate that immature T-cells are deficient in nucleotide excision repair whereas the majority of mature peripheral blood lymphocytes exhibit such repair.

Pollen-induced chemiluminescence: inhibition by serum from allergic individuals.

The interaction between pollen grains, polymorphonuclear leukocytes (PMNs) and serum results in the formation of "pollen rosettes" and the production of chemiluminescence (CL). Significantly more CL is produced by cells exposed ot pollen and sera from nonallergic individuals compared with sera from allergic individuals. The source of the PMNs, however, has no effect on the CL produced, When IgG is isolated from the sera of allergic individuals and added to the test system, a large CL response is seen that is inhibited by the IgG-depleted fraction. No similar inhibition is produced by the IgG-depleted fraction of sera from nonallergic individuals. The inhibitor of CL in sera from allergic individuals appears to be IgE, since its removal leads to an enhanced CL response. These results suggest that competition for a limited number of binding sites on pollen grains exists between pollen specific IgG and IgE antibodies in serum from allergic patients.

Toxoplasmosis in nude mice.

Immunity to the intracellular protozoan, Toxoplasma gondii, in mice is of the premunition type. Chemoprophylaxis with sulfadiazine normally permits mice to develop immunity to virulent organisms. However, nude (nu/nu) mice, which lack the thymus, failed to develop immunity to toxoplasma during 3 weeks of drug therapy while their hirsute littermates developed immunity during this period. When nude mice were injected intraperitoneally with thymus cells from hirsute littermates, they became able to develop immunity to toxoplasma during drug prophylaxis. The injection of bone marrow cells or high-titered specific antibody did not prolong survival after sulfadiazine was discontinued. Therefore, it appears that immunity to toxoplasma in mice is dependent upon active cellular immunity while the role of antibody is uncertain.

Cellular immunity to toxoplasma and besnoitia in hamsters: specificity and the effects of cortisol.

The inhibitory effects of cortisol on cellular immunity were studied in vitro by using hamster peritoneal exudate cells. Two obligate, intracellular protozoa--Toxoplasma gondii and Besnoitia jellisoni-- were used to control for specificity of effects. Results indicate that immune lymphocytes specifically confer immunity to (or "arm") macrophages that specifically express immunity. This arming can be inhibited by 5 microng of cortisol per ml. Macrophages that have been armed already will continue to express immunity (by limiting parasite growth specifically) in the presence of 5 microng of cortisol per ml. Cortisol levels of 20 microng/ml are required to inhibit the expression of immunity by armed macrophages. It was also found that lymphocytes, from hamsters given 20 mg of cortisol subcutaneously 2 days before the harvest of cells, did not arm macrophages, whereas macrophages from these same animals could be armed by immune lymphocytes from untreated hamsters. Therefore, it was concluded that in relation to cellular immunity, lymphocytes are more sensitive to cortisol than are macrophages. Since antibody to these parasites is almost always present in vivo, we also tested the effects of cortisol on the disposition of antibody-modified organisms by activated (not armed) macrophages, and found that 50 microng of cortisol per ml was needed to inhibit macrophage effects on antibody-treated organisms.