Repeated skin tests in guinea pigs with fluorescein visualization.

A method is presented for immediate hypersensitivity skin testing of guinea pigs using fluorescein as a contrast medium. The method allows repeated skin tests of individual animals. Results are compared with those obtained using Evans blue dye, which leaves animals unsuitable for later skin testing. The two methods give very similar direct skin test results.

Respiratory hypersensitivity to Ascaris extract in guinea pigs sensitized by aerosol.

Guinea pigs exposed via the respiratory route to Ascaris suum extract in aerosol form became hypersensitive. The hypersensitivity was detectable by inhalational bronchial provocation testing using a noninvasive plethysmography, by chopped lung histamine release, and by passive cutaneous anaplylaxis. The antibody responsible for the hypersensitivity seems to be directly associated with pulmonary tissue. A locally produced cytotropic pulmonary antibody, probably IgG or IgE may be causal. Histopathology included only a moderate pulmonary eosinophilia. Individual variability in susceptibility to experimental allergic asthma may be controlled by both physiologic and immunologic reactivities.

A noninvasive technique for measurement of changes in specific airway resistance.

A simple noninvasive technique for measuring specific airway resistance (airway resistance X thoracic gas volume) in unanesthetized guinea pigs is described. Specific airway resistances measured by this technique correlated well (r = 0.81) with the resistances obtained using a pleural catheter pressure measurement over a wide range of airway resistances. This range of resistances was generated by exposing the pigs to an aerosolized histamine bronchial challenge. The average specific airways resistance in unchallenged pigs was 1.24 +/- 3.47 cmH2O/s, somewhat lower than found by others, probably reflecting in part our larger pigs and in part some uncertainty in the absolute value of resistance inherent in our measurement technique. This technique is particularly useful in bronchial challenge experiments because of its sensitivity to acute changes in airway resistance.

Enhancement of IgE antibody formation in the rabbit by adrenergic antagonists.

The effects of adrenergic antagonists on the humoral immune response of rabbits to egg albumin was studied. Propranolol, a beta-adrenergic antagonist, when administered at a dosage of 20 mg/kg of body weight, enhanced both passive hemagglutinating and IgE (passive cutaneous anaphylaxis) antibody formation. Phenoxybenzamine, an alpha-antagonist, at 0.4--40 mg/kg had a similar adjuvant effect. A marked delay in the immune response was noted with high dosages of phenoxybenzamine. Possible mechanisms of the adjuvant effects of these drugs are discussed.

Studies of the paw test and tumor-associated immunosuppression in mice.

Specific paw test reactivity to tumor cells was transferred to normal mice using lymphoid cells or serum from mice with a growing or surgically excised methylcholanthrene-induced transplantable sarcoma. When the donors had been sensitized to PPD and to tumor, normal recipients of lymphoid cells became reactive by specific paw test to tumor cells and PPD. Normal recipients of serum from the same donors also became reactive to tumor cells. Normal recipients of serum from tumor-bearing mice developed depressed PHA paw tests. Adoptive transfer with cells or serum of paw test reactivity to tumor and PPD was unsuccessful when recipients had large tumors. This was the case when the recipients had either tumor of the same line or that of a separate line that did not cross-react antigenically.

Relationship between the response to complete freund adjuvant, phytohemagglutinin, and subsequent tumor growth in mice.

Groups of inbred C3H mice selected on the basis of strong or weak PPD reactions after sensitization with complete Freund adjuvant had significantly different reactions to PHA. The growth rate of a methylcholanthrene-induced tumor, previously shown to elicit a cell-mediated immune response, was significantly different in these two groups of mice. The basis for the marked variation observed between members of an inbred mouse strain in response to CFA is not understood but may bear an important potential relationship to tumor growth.