Figure 4.

Inhibition of passive cutaneous anaphylaxis in Wistar rats by anti-CD81. Male Wistar rats were injected intradermally with (A) 25 ng DNP-specific IgE mixed with 50 μg anti-CD81 mAb 5D1 (mouse IgG1) or control mouse IgG1 mAb (MOPC 31c; specificity unknown) or (B) 100 ng DNP-specific IgE alone. Mice receiving 100 ng IgE alone were reinjected 21 h later with buffer, 5D1, or a mouse IgG1 control mAb to LFA-1β chain (anti-CD18; WT.3). Control sites (no IgE) received buffer or 50 μg of IgG1 subclass mAb. 24 h after IgE injections, 1 mg of antigen (DNP–HSA; 1 mg/ml in PBS containing 1% Evan's blue dye) was injected intravenously and rats were killed 30 min later. Extravasation of Evan's blue dye into the skin was quantified by A₆₁₀ measurements of serial hot formamide extractions (54) of minced punch biopsies (2.5 cm²/ site). Sample A₆₁₀ values were converted to micrograms of Evan's blue dye based on standard curves of Evan's blue A₆₁₀ absorbance in formamide. Results taken from three injected sites per condition (IgE plus buffer or antibody) or a single site (IgG1 controls without IgE) from a single rat and expressed as mean micrograms of Evan's blue dye ± standard deviation. Comparable results were obtained on two additional rats for both experiments shown. Statistical significance was determined using an unpaired Student's t test: *, P <0.05; **, P <0.01 (actual values: A, P = 0.024 versus MOPC 31c controls; B, P = 0.009 versus anti-LFA-1β controls).