Blood, 1972, Vol. 39, No. 4, pp. 568-574.
© 1972 American Society of Hematology, Inc.
Porphyrin Synthesis by Cultured Lymphocytes
Alan S. Josephson 1,
Richard D. Levere 1,
Ivan Lowenthal 1,
Fred Swerdlow 1, and
Mark Ginsberg 1
1 Department of Medicine, State University of New York, Downstate Medical
Center, Brooklyn, New York.
Peripheral lymphocytes were cultured
in the presence and absence of phytohemagglutinin (PHA). Porphyrin synthesis was visually estimated by
fluorescence and quantitated by fluorometry. No visual fluorescence was
noted in cells cultured with or without
PHA. Addition of 
-aminolevulinic acid
(ALA) to cultures of either transformed
or nontransformed lymphocytes resulted in fluorescence, indicating porphyrin synthesis. Certain sex steroid
metabolites stimulate porphyrin synthesis by induction of the rate-limiting
enzyme ALA synthetase. Erythropoietin
also increases the rate of heme
synthesis. Phytohemagglutinin-transformed and nontransformed cells were
cultured with the addition of either
11-keto pregnanolone or erythropoietin, and neither agent induced porphyrin synthesis. Only when ALA was
added to the culture medium was the
measured fluorescence statistically
greater than in control cultures. These
studies indicate that the enzymes of
porphyrin synthesis distal to ALA synthetase, the rate-limiting enzyme, are
present in all cultured lymphocytes.
The rate-limiting enzyme is not induced by PHA transformation, even in
the presence of a 5-
-H steroid metabolite or erythropoietin.
Submitted on June 16, 1971
Revised on October 1, 1971
Accepted on October 22, 1971
