Serological Technique: Physical Agents Producing Allergic Reaction

Agents like light, heat, cold and trauma also act like the chemicals and give rise to physical allergy. Undetected physical allergy may be responsible for many obscure ailments. Tests for physical allergy : (1) Cold test.? Dip the subject's hand and part of forearm in water between 9 and 10?C. for 6 minutes. The skin blanches. Remove the limbs from the water. Pallor changes to redness, and a slight oedema and a local rise in temperature (judged by touching the other limb for comparison)