cc

September 10. 1959

Dr. Robert White
Department of Bacterlology
London Hospital

London E. |

ENGLAND

Dear Dr. White:

With a:étogles for the delay, many thanks for your Kodachrome
of double florescent staining. It Is certainly very Impressive.
| do recall your precautions concerning the variation of hue
with intensity. There Is one spot on the photograph, quite
out of focus, that looks as If It might be an Intermediate
yellow color. The one question that people (for example Dr. Cohn)
are going to ask is whether you can say from your own experience
what a doubly stained cel! wouldlook IIke. This could be verified
experimentally by an obvious method of applying the two colored
conjugates of a single antibody to specimens like the section

photographed.

Dr. Nossal has Just recently arrived from Australia and is oo
very energetically setting about to organize the extension of aa
his program. One item we have discussed Is the modification of r
florescent staining technique to cell suspensions In preference
to sections. We discussed this !ast summer; have you had any wh

experlence on this polnt?

Dr. Cohn's results are more Impressive than ever. ,He has
now examined cells from animals exposed to three distinct antigens ~”
and finds a quite respectable proportion of cells which are
yielding two of the three antibodies in the various combInations.
He had a rather low expectation for a triple producer; In any case
he did not find any. The "grand difference'' between the experiments
continues, in my own mind, to be evidently the duration of exposure
since all of Cohn's animals have seen at least one of the antigens
3 year or more prior to thelr final course of Immunization.
We are debating how worthwhile It would be to put In a strong
effort to verify that this is the basis of the difference tn
the results.

We have been spending much of our time during the past
weeks in moving Into our new quarters in the Just finished
Medical Center, which Its one of the excuses | must offer In
apology for the delay in this acknowledgment. Or. Nossal and
1 will surely look forward to keeping In close touch with you.
Please give my best wishes again to Bob Schilling.

Yours sincerely,

Joshua Lederberg
Professor of Genetics