IMMUNOCYTOCHEMICAL IDENTIFICATION OF IMMATURE RAT PERITONEAL MAST-CELLS USING A MONOCLONAL-ANTIBODY SPECIFIC FOR RAT MAST-CELLS

The lack of immunological or morphological markers makes identificatio n of immature mast cells difficult. In the present study we have used a rat mast cell specific monoclonal antibody (mAb AA4) to immunolabel mast cells during repopulation of the peritoneal cavity. Peritoneal ce lls were collected six days after injection of distilled water and exa mined by light and electron microscopy. mAb AA4 stained immature mast cells in various stages of maturation including a population of very i mmature mast cells that could not be identified using conventional sta ining methods. These cells had virtually no cytoplasmic granules and p eripherally located located nuclei. Thus, immunolabeling with mAb AA4 has revealed a population of very immature mast cells not previously r eported during repopulation of the peritoneal cavity.