A common problem for the purple leaf plum tree is blossom blight, in which first the flowers, then young leaves, turn brown and wither, according to Grow Fruit by Alan Buckingham.
Once activated, helper T cells start to divide and to produce proteins that activate B and T cells as well as other immune cells. The killer T cell is specialized in attacking cells of the body infected by viruses and sometimes also by bacteria.
Cytotoxic T-cells: Cytotoxic T-cells, also called CD8 T-cells, destroy cells that are infected with viruses and tumors. Their T-cell receptors, located on their cell surfaces, are made up of CD8 glycoproteins. They contain pouches, called granules, which are filled with chemicals that kill infected cells on contact.