August Im 1959
Dear Dr. Sterz!:
Thank you for your Interesting letter of July 23, just received.

Perhaps Miss O'Connor at Ciba/London will have been able meanwhile
to send you a copy of my written reply as submitted for the symposium
publication. Let me say first how Important ! think your experiment Is,
since {t does represent almost the only quantitative evaluation of cellu-
lar performance. At the same time ! would not become too frantic over
tts Implications until some of the Indicated numbers were more explicitly
conf lgmed.

If we accept your calculations, which sre perhaps favoreblg biased, we
may then come to the main Issue, the potential productivity of a single anti-
body-forming cell. You quote Berenblum at 6 x 10-!2 g/day but | wonder If
this 1s not too small. Dixon calculated @ yield ebout 10° Og per cell
(J Exp Med 102:579)(he writes; g, by the way, for mg): this figure
would be based on every cell being active; on the other hand, it does not
take account of possible proliferation. In any cease, | would assume that
a plasma cell has a weight of about 1079 g., and would expect It to be
capable of producing # major fraction of its own weight in antibody. It
will, of course, be Important to get precise values for this parameter, as'
should be possible before long. In rabbits, a globulin pool of about |
gm Is turned over In 5 days by 5-10 gms. of lymphoid cells. This would
give a basal rate of ebout 2 x TO" 1) gm ab/cell/day and | would think this
would be much higher In specially stimulated and mature plasma celés.

1 do not heve Berenbaum's peper close at hand; our medical school Jibrary
Is preparing to be moved to @ new building on the campus here-- where | hope
to have some opportunity to show you sround before too long.

Turning to your calculations, | would read 28 x kO w 10,240 cells., after
h days. But the total number of call-days will be your figure ~ 5000. 1 do
not know what to think of the expected rate of division; ! agree that you ere
probably not underestimating It, but these cells may well do better, for a time,
than Puck's tissue cultures. 1 do not think 5000 (Talmace's figure) Is un-
realistic for the ratio of (total antibody species)/(antibody species reacting
with your antigen), which is the relevant figure. Perhaps, as we discussed, the
ratio Is even smaller in your particular case owing elther to past experience of
the donor rabbits with cross-reacting antigens, or to a genetically determined
preference that would have nad some adaptive value In evolution.

! will of course be very pleased to hear of the progress of your
experiments along these lines. Thank you for sending me the comment, and
please do let me know(when the right time comes) how | can facilitate your
visiting us. § am not now planning to visit Europe next year, but twill
likewise keep you Informed of any usef6} opportunity. Or. Nossal is arriving
In a few weeks to continue our collaboration. You will doutctless see him
in 1961 (t hope sooner) If he can arrange to return to Australia via Central
Europe.
: Yours cordially,

}

Joshua Lederberg

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