MOLECULAR CHARACTERISTICS OF THE EFFECTOR PATHWAYS OF IMMUNOLOGICAL RESPONSES 
Edward J. Goetzl, M.D., Investigator 
Dr. Goetzl's studies of the mediators of effector 
pathways of the immune system this year have iden- 
tified high-affinity receptors specific for leukotrienes 
and platelet-activating factor (PAF) on human neural 
cells, revealed the genetic message encoding human 
lymphocyte receptors for the neuropeptide vasoactive 
intestinal peptide (VIP), and defined the range of 
functions of the human monokine designated fibro- 
blast-activating factor (FAF) and the expression of FAF 
in fibrosing diseases. 
L Neural Receptors for Leukotrienes and PAF. 
Dr. Goetzl and his colleagues have shown re- 
cently that central nervous system tissue and cul- 
tures of isolated human neural cells generate both 
leukotrienes and PAF. Physiological stimuli and 
trauma increased the levels of neural generation of 
the lipid mediators, and specific antagonists of some 
of the mediators were shown by Dr. F. H. Valone 
and Dr. Goetzl to reduce the neurological damage 
after trauma. That the effects of locally generated 
lipid mediators on several neural functions are de- 
pendent on their recognition by stereospecific re- 
ceptors was supported by the results of direct bind- 
ing studies. Dr. Catherine Koo and Dr. Goetzl found 
that the U-373 line of human glioblastoma/astro- 
cytoma cells bound [^H]LTB^ (leukotriene and 
[^H]LTC^ specifically, with respective values of 
20-50 and 60-80 nM. Similarly, they observed that 
NBII human neuroblastoma cells bound [^HJLTB^ 
and [^H]LTC^ with respective values of 30-60 
and 20-40 nM. The receptors for leukotrienes on 
both types of neural cells resembled the low-affmity 
subsets of the corresponding receptors of human 
neutrophils and exhibited the same specificity. 
Neural receptors for PAF are coupled principally 
to cellular growth and differentiation and, in con- 
trast to the leukotriene receptors, differed in affin- 
ity and specificity from monocyte and platelet re- 
ceptors for PAF. Drs. Valone and Goetzl found that 
NGP neuroblastoma cells bear a mean of 850 recep- 
tors for PAF, with a mean of 1.2 pM, that recog- 
nize 2-O-methoxy-PAF with far higher affinity than 
monocyte receptors. The capacity of both 2-O-me- 
thoxy-PAF and PAF to stimulate NGP cell prolifera- 
tion and neurite outgrowth confirmed the unique 
specificity of the neural receptors for PAF. 
II. Mediation of Immunity by Somatostatin, VIP, and 
Mast Cell-Derived Variants of VIP. 
The capacity of somatostin (SOM) and VIP to 
suppress T cell proliferative and synthetic activities 
and to inhibit selectively the synthesis of IgA and 
IgM by mixed lymphocytes is a function of specif- 
ic recognition of the neuropeptides by separate 
subsets of T and B cell receptors. Dr. Goetzl and 
Dr. Sunil P Sreedharan focused recently on two 
lines of human cultured lymphocytes that bind 
SOM and VIP: the Jurkat leukemic T cell and the 
U-266 myeloma cell. They found that Jurkat T cells 
express two sets of a mean of 144 and > 100,000 
SOM receptors, with respective values of 3 pM 
and 66 nM, and one class of a mean of 12 x 10^ 
VIP receptors with a of 5.2 nM. U-266 cells 
similarly bear two sets of a mean of 1,295 and 
> 100,000 SOM receptors, with respective values 
of 5 pM and 100 nM, and one class of 41 x 10^ 
VIP receptors with a of 7.6 nM. The specificity of 
the lymphocyte receptors for VIP, determined by 
Drs. Goetzl and Sreedharan from the rank order of 
affinity of a series of substituents and analogues of 
VII^ differed from that of neural and endocrine cell 
receptors. Expression-cloning techniques are being 
used to investigate the genetic determinants of the 
Jurkat and U-266 cell receptors for VIP, in order to 
elucidate the structural bases for their distinctive 
specificity. 
U-266 and Jurkat cell cDNA libraries were size- 
selected, inserted into the CDM8 expression vector, 
transfected into COS cells, and enriched for VIP re- 
ceptor message by flow cytometric selection, using 
an antibody to the 47 kDa affinity-crosslinked VIP 
receptor protein of Molt-4b human T lymphoblasts. 
Drs. Goetzl and Sreedharan, in collaboration with 
Dr. Sue O'Dorisio, then identified and isolated a 
positive transfectant containing a 405 bp cDNA that 
endowed COS cells with both specific binding of 
the anti-VIP receptor antibody and high-affinity 
binding of [^^^I]VIP Several 800-1,500 bp cDNAs 
that comprise the full-length cDNA for the VIP re- 
ceptor have been recovered from the U-266 library, 
by employing the 405 bp cDNA as a (^^P) probe for 
hybridization analyses of Escherichia coli trans- 
formants. 
Continued 
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