The late phase of a Type 1 reaction (which develops 8–12 hours and is mediated by mast cells) should not be confused with delayed hypersensitivity Type IV allergic reaction (which takes 48–72 hours to develop and is mediated by T cells).
The late stage of a Type 1 reaction, which occurs over 8-12 hours and is driven by mast cells, should not be mistaken for a delayed hypersensitivity Type IV allergic reaction that develops over 48-72 hours and is triggered by T cells.