The distribution of the immune cells and of the virus in FIP lesions were also investigated immunohistochemically with the avidin biotin complex ( ABC ) method , using antibodies against the FIP virus ( FIPV ) , myelomonocytic ( MAC 387 ) and lymphoid ( CD 3 , CD 4 and CD 8 for T cells and IgM and IgG for B cells ) antigens . ^^^