penn

June 21, 1960

Or. Carl Ojerass!
Syntex, S.A.
Apartado 2679
Mexico, O.F.

Dear Or. Djerass!:

Many thanks for your continuing Interest In our sterold work. | am
now In @ posit lon to make a couple of definite statements about our results.

1) A single dose of 20 mg. of hydrocortisone alcoho! USP. microfine
Is approximately an L.D. 50/10 days in our mice. With such a huge dose,
the antibody production against our standard bacterial antigen Is only
moderately diminished -- a@ reduction of 2 to & logso- This Is considerably
less reduction than Is achieved by an L.D. 10, for example of whole body
Irradiation.

2) a single dose of 25 mg. of prednisone or dally doses of up to
5 ag. of prednisone web virtually Ineffective. (1 - 2 logso depression).

While these results are a little disappointing from our point of view,
I think the differences between soluble and Insoluble sterold preparations
may turn out to be of some Importance In human therapy. We still cannot
exclude the transport of drug particles to specific sites by scavenger cells
as a factor In achleving Immune depressfon.

1 do feel | want to pursue this question a little further with differ-
ent antigens. | belleve Dr. Lederberg has asked you for some soluble hydro-
cortisone alcohol. Would It also be possible to send us a fairly large
supply (e.g. 50 gus.) of the hydrocortisone alcohol U.S.P. microfine as
In order no. 31079 (Roussel) and a smaller amount (e.g. 10 gas) of the
Identical compound but as a large crystal. ! also would appreciate a little
Information as to how to prepare a ualform, non-Ircitant suspension Of these
insoluble products. We have had little success using various oleates and

Artacel A as emulsifying agents.

| do hope we may meet during your next Stanford visit. Again, my thanks
for your cooperation.

With best wishes,

Yours sincerely,

Gus Nossal]
Assistant Professor of Genetics