BBLEC-P (003)

• P BLOOD GROUP = P1PK (ISBT #003)

  • comprised with P, P1, Pk, Luke = these antigens are not considered as a single blood group system.
  • P1 and Pk = assigned to P1Pk blood group system (003)
  • P = assigned to globoside blood group system (028)
  • LKE and PX2 = assigned to globoside collection (209)
• P BLOOD GROUP = P1PK (ISBT #003)

  • introduced by Landsteiner and Levine in 1927 = via injection of human RBCs to rabbits to produced new antibodies.
  • the antibody was initially called Anti-P = this finding divided the human RBCs then into P+ and P-
• P BLOOD GROUP = P1PK (ISBT #003)

  • In 1951, Levine and colleagues described Anti-Tja which is now known as anti-PP1Pk.
  • Antibody to a high-prevalence antigen that Sanger later showed was related to the P blood group.
  • influenced the renaming and formation of the P blood group system
  • P+ becomes P1 and P- becomes P2, the rare P null become "p"
• P BLOOD GROUP = P1PK (ISBT #003)

  • in 1959, Matson and coworkers described the antigen Pk.
  • the antigen is expressed on all RBCs except those of very rare p phenotypes
• P BLOOD GROUP PHENOTYPES

  • there are 2 common phenotypes = P1 and P2
  • P1 = describes RBCs that react with anti-P1 and anti-P
  • P2 = describes RBCs that do not react with anti-P1 but reacts with anti-P
• P BLOOD GROUP PHENOTYPES

  • there are 3 rare phenotypes = p, P1k, and P2k
  • p phenotypes do not react with anti-P1, anti-P, anti-Pk
  • p phenotypes (P null) = rare; common in Japan, North Sweden, and Ohio
  • P1k phenotypes = reacts with anti-P1 and anti-Pk but not with anti-P
  • P2k phenotypes = reacts with anti-Pk but do not react with anti-P1 or anti-P
• P BLOOD GROUP ANTIGENS

  • synthesized by glycosyltransferases (adds sugar to a precursor substance)
  • precursor substance to P1 is also precursor for type 2H chains that carry ABH antigens.
  • Genes responsible for the formation of P1 and ABH antigens are independent
• P BLOOD GROUP ANTIGENS

  • P1, P, and Pk = found on RBCs, WBCs
  • P can be found on platelets, epithelial cells, and fibroblasts
  • P and Pk have been found in plasma as glycosphingolipids and glycoproteins in hydatid cyst fluid.
• P BLOOD GROUP ANTIGENS

  • P antigens are resistant to papain, ficin, dithiothreitol, chloroquine, and glycine-acid EDTA.
  • reactivity of antibodies are greatly enhanced by testing with enzyme-treated RBCs
• P BLOOD GROUP ANTIGENS

  • P1 antigen = poorly expressed at birth (may even take 7 years for full expression)
  • Antigen strength varies = from inheritance to race
  • Differences among P1+ individuals may be controlled genetically or via homozygous/heterozygous inheritance.
  • Blacks have stronger expression of P1 than whites.
  • Deteriorates rapidly on storage
• P BLOOD GROUP ANTIGENS

  Synthesis

  • the common precursor is lactosylceramide (Gb2, ceramide dihexose, or CDH)
  • Pk synthesis is carried out by 4-a-galactosyltransferase (Gb3, Pk synthase)
  • P synthesis formation is carried out by 3-b-N-acetylgalactosaminyltransferase (Gb4 synthase) = converts Pk to P
• P BLOOD GROUP ANTIGENS

  1. Lactosylceramide (Gb2) = lactotriaosylceramide & Pk antigen Globotriaosylceramide (Gb3)
  2. Lactotriaosylceramide = paragloboside (type 2 precursor) = P1 antigen & ABH antigen
  3. Pk antigen Globotriaosylceramide (Gb3) = P antigen Globoside (Gb4) = LKE
• LUKE ANTIGENS (LKE)

  • Tippett and colleagues described an antibody in the serum of a Hodgkin's lymphoma patient in 1965.
  • Divided the population to 3 phenotypes --> 84% = Luke (+); 14% = Luke (w); 2% = Luke (-)
  • Group under P blood group since the antibody reacted in all RBCs except 2% of P1 and P2 phenotypes
  • All p and Pk phenotypes are Luke (-)
• P BLOOD GROUP ANTIBODIES

  Anti-P1

  • common, naturally occurring IgM antibody in the serum of P1(-) individuals = poorly developed on fetal RBCs.
  • weak, cold-reactive saline agglutinin (reacts at 4C)
  • Stronger types reacts at room temp
  • Rare types reacts at 37C and binds complement = detected at AHG phase (polyspecific reagent) and may cause in-vivo RBC destruction, immediate or delayed HTRs
  • Reaction varies especially if old RBCs are used.
• P BLOOD GROUP ANTIBODIES

  Anti-PP1Pk

  • formerly Anti-Tja
  • First discovered in the serum of Mrs. Jay, a "p" individual with adenocarcinoma of the stomach = the tumor cells carried P system antigens; the antibodies had cytotoxic properties that may have helped prevent metastatic growth post surgery.
  • Produced by "p" individuals early in life without RBC sensitization and reacts with all RBCs except those of the "p" phenotype.
• P BLOOD GROUP ANTIBODIES

  Anti-PP1Pk

  • components (anti-P, anti-P1, and anti-Pk) are IgG and IgM = can be separated by adsorption; reacts over a wide thermal range and bind complement
  • can cause HTRs and HDFN
• P BLOOD GROUP ANTIBODIES

  Alloanti-P

  • a component of anti-PP1Pk in "p" individuals
  • naturally occurring in the sera of Pk individuals