Lipid-mediated hemagglutination.

Title

Identifier

AAI9510701

identifier

9510701

Creator

Patrikios, Ioannis S.

Contributor

Adviser: Charlotte S. Russell

Date

1994

Language

English

Publisher

City University of New York.

Subject

Chemistry, Biochemistry | Health Sciences, Nutrition | Health Sciences, Pharmacology

Abstract

Contradictory reports in the literature about the hemagglutinating activity of dioleoylphosphatidylethanolamine (DOPE) were partially explained in this laboratory by Pi-Shiang Lai. Pure DOPE does not agglutinate red cells, but aged or heated samples agglutinate several species of red cells. It was also found that oleic acid (cis-S-octadecenoic acid, OA) exhibited the same hemagglutinating activity under the same conditions and presented a simpler system to investigate.;OA itself has a very low agglutination titer but lyses red cells at higher concentrations. When mono-unsaturated fatty acids are heated in air, they form hemagglutinins. Octadecenoic acid with a cis-6 or cis-9 double bond has a higher agglutination titer than cis-11-octadecenoic acid. Stearic acid does not become a hemagglutinin on heating. Hydroxy-monounsaturated fatty acids, such as ricinoleic (cis-12-hydroxy-{dollar}\Delta{dollar}-9) and ricinelaidic (trans-12-hydroxy-{dollar}\Delta{dollar}-9) hydroxy acids are not hemagglutinins unless they are heated. Rabbit, rat and chicken erythrocytes (RBCs) give the highest titers but RBCs of other species are also agglutinated. OA was chosen for further study. Its specific titer against rat RBCs increases with time of heating in air. Sialidase treatment of the red cells increases the titer. Removal of cations does not alter the titer but addition of Ca{dollar}\sp{lcub}2+{rcub}{dollar} or Mg{dollar}\sp{lcub}2+{rcub}{dollar} lowers the titer. Thin-layer chromatography (TLC) and mass spectrometry (MS) show that higher molecular weight compounds are formed on heating OA and that hemagglutination activity is associated with these materials.;Synthetic linear oleic dimers (obtained by oxidation of OA with di-tert-butyl peroxide and commercial OA dimers (Emery, Cincinnati, OH and Unichema, Chicago, IL) and a commercial preparation of OA trimer mixed with polymer (Emery) which contained linear cycloaliphatic and aromatic dimers and trimers all have high hemagglutination titers against rat RBC. A cyclic, long-chain dicarboxylic acid, 5(6)-carboxy-4-n-hexyl-2-cyclohexene-1-octanoic acid (Westvaco, North Charleston, SC), gives no lysis and a very low titer unless heated. Filtration of all of these fatty acids through a 0.2 {dollar}\mu{dollar}m membrane does not change the titer.;Light microscopy was used to characterize and visualize the agglutination process with rat RBCs. Large multilamellar vesicles are observed when OA is dispersed in saline at pH 7.4 at concentrations of 1-4 mg/mL, sonicated and filtered through Whatman 41 paper. Agglutination without lysis or fusion is observed for low concentrations of heated OA and C18 dimers and C18 trimer-polymer preparations and no large vesicles are seen. A pH study (pH 6-9) of heated OA, C18 dimer and C18 trimer-polymer against rat RBCs shows that the specific titer increases with pH from 6 to 9, beyond which range at either end the RBC are not stable. It is concluded that oligomeric fatty acids with two or more hydrophobic chains of seven or more carbons and more than one carboxyl group are agglutinins at physiological pH. Near infrared studies with dimers at high and low concentrations suggest that the carboxyl and carboxylate groups form intermolecular hydrogen-bonds. This suggests that they can form hydrogen-bonded aggregates of various kinds, possibly networks. Agglutination by the dimer may result from the insertion of two hydrophobic side chains into adjacent RBC membranes or from complete insertion of dimer into RBC membranes and alteration of their properties. The carboxyl groups may also play a role in the process by interacting with polar headgroups of phospholipids in the RBC membrane.

Type

dissertation

Source

PQT Legacy CUNY.xlsx

degree

Ph.D.

Item