Clin. exp. Immunol. (1984) 57, 502-5 10.

NK cell activity and skin test antigen stimulation ofNK like CMC in vitro are decreased to different degrees in

pregnancy and sarcoidosis

D. TARTOF, J. J. CURRAN, S. L. YANG & C. LIVINGSTON Departments of Medicine,Obstetrics and Gynecology, The University of Chicago, Chicago, Illinois, USA

(Acceptedfor publication 23 February 1984)

SUMMARY

Peripheral blood mononuclear cells (PBMNC) isolated from normal subjects, pregnantwomen and patients with sarcoidosis were assayed for natural killer (NK) cell activity onday 0 and for NK like cell-mediated cytolysis (CMC) after 5 days of exposure, in vitro toCandida antigen, purified protein derivative (PPD), and human leucocyte interferon(IFN). Pregnant women and women with sarcoidosis had significantly decreased levels ofNK cell activity compared to normal women. Pregnant women had the lowest mean NKcell activity. Cells from women with sarcoidosis and from pregnant women also had lowerlevels of killing than those from the normal women after in vitro stimulation ofNK likeCMC with Candida antigen, PPD and IFN. The lowest stimulations ofNK like killingoccurred in the cells from women with sarcoidosis. Skin test antigen stimulation ofNKlike CMC in vitro and the DTH response in vivo were strongly correlated for both Candidaantigen and PPD in the sarcoidosis patients. There was no correlation between the level ofNK cell activity in the PBMNC of sarcoid patients on day 0 and the amount ofNK likeCMC that was present in cells from those patients after 5 days of culture with Candidaantigen, PPD or IFN. A significant correlation was found, however, between Candidaantigen stimulation of NK like CMC and IFN stimulation of NK like CMC in bothpregnant and sarcoid groups. Reduced NK cell activity on day 0 in a given patient thus didnot necessarily indicate that skin test antigen or IFN stimulation ofNK like CMC on day5 would also be depressed. In addition, NK cell activity was often noted to be normal inpatients with depressed in vitro stimulation of NK like CMC.

Keywords natural killer cell activity pregnancy sarcoidosis

INTRODUCTION

There is growing evidence that natural killer (NK) cell activity and antigenically stimulated NK likecell-mediated cytotoxicity (CMC) may be involved in a wide range of cell-mediated immunephenomena. Although a primary role in tumour surveillance was initially hypothesized for NK cells(Takasugi, Mickey & Terasaki, 1973; Herberman & Holden, 1978; Kiessling & Haller, 1978; Kasaiet al., 1979), recent studies have suggested that they may also be involved in transplant rejection(Lipinski et al., 1980; Clark & Harmon, 1980; Guillou et al., 1982; Ono, Kerman & Kahan, 1982),graft versus host disease (Lopez et al., 1979; Dokhelar et al., 1981), resistance against viral infection(Bancroft, Shellan & Chalmer, 1981) and 'autoimmune' disease (Goto, Tanimoto & Horiuchi,

Correspondence: Dr David Tartof, Department of Medicine, Box 404, University of Chicago, 950 East 59thStreet, Chicago, Illinois 60637, USA.

502

NK cells in pregnancy and sarcoidosis 5031980; Barada, O'Brien & Horwitz, 1982). Recently, various groups have shown that a variety ofagents including viruses (Hutt-Fletcher & Gilbert, 1981) and cellular alloantigens (Seeley et al.,1979) stimulate NK cell like CMC in human peripheral blood mononuclear cell (PBMNC)populations exposed to those substances in vitro. The killing was termed 'NK like' because thecytotoxic cells stimulated in this manner not only killed target cells susceptible to cytolysis by NKcells but also target cell lines resistant to NK cell cytolysis. Also, unlike NK cells, the NK like cellsstimulated in vitro often did not bear receptors for the Fc portion of IgG (Hutt-Fletcher & Gilbert,1981; Seeley et al., 1979). In addition, it was unlikely these killer cells were derived from the NK cellsubset since NK like killing could be stimulated in cell populations depleted ofNK activity (Seeleyet al., 1979). Studies in our laboratory demonstrated that skin test antigens (STA) stimulated NKlike CMC in human PBMNC exposed to those antigens in vitro (Tartofet al., 1980; Tartof, Check &Medof, 1982) and that in normal individuals there is a close correlation between the magnitude ofthe skin test response to Candida antigen in vivo and the stimulation ofNK like CMC by Candidaantigen in vitro (Tartof et al., 1980). Since cell-mediated immunity is thought to be altered inpregnant women and in patients with sarcoidosis, many of whom are women of child bearing age(Teirstein & Lesser, 1983), we decided to examine NK cell activity and in vitro stimulation of NKlike CMC in these two conditions.

In addition, since patients with sarcoidosis frequently display decreased DTH responses to awide variety of skin test antigens (i.e. are anergic) (Friou, 1952; Sones & Israel, 1954; James, 1966),we sought to compare STA stimulation of NK like CMC in vitro with stimulation of NKresponse in vivo in these patients.

We found (1) as a group, normal women had lowerNK cell activity than normal men. (2) WhileNK cell activity in pregnant women and women with sarcoidosis was reduced below that found innormal women, the greatest reduction occurred in pregnancy. (3) That STA and IFN stimulation ofNK like CMC in vitro were also reduced in pregnancy and sarcoidosis, however, unlike the situationfor NK cell activity, the greatest decrease occurred in sarcoidosis. (4) There was no correlationbetween NK cell activity and STA or interferon (IFN) stimulation ofNK like CMC in sarcoidosisor pregnancy. (5) Although both responses were reduced there was a strong correlation between theDTH response in vivo and the stimulation ofNK like CMC in vitro with both PPD and Candidaantigen in the patients with sarcoidosis. There was no correlation, however, between NK cellactivity and the DTH responses in those same patients.

MATERIALS AND METHODS

Subjects. The study groups consisted of 21 normal pregnant women, 10 adult patients (ninewomen and one man) with biopsy proven pulmonary sarcoidosis and 23 age matched normal adults(15 women and eight men). None of the subjects were taking hormones or other medications.

Reagents. Sterile solubilized Candida albicans was obtained from Hollister Steir Laboratories(Yeardon, Pennsylvania, USA) as a concentrated allergenic extract with 50% glycerin aspreservative. The concentrated extract was diluted 1:10 with phosphate-buffered saline (PBS) foruse in skin testing. Since glycerin was known to inhibit cellular stimulation in vitro, a portion of theextract was dialysed overnight against PBS with the original volume held constant. The dialysedextract was sterilized by passage through a 0 2 pm pore size filter and stored at -70'C. Thispreparation was used for cellular stimulations in vitro. Purified protein derivative (PPD) obtainedfrom the Ministry of Agriculture and Fisheries (Kent, UK) was reconstituted in PBS, sterilized bymeans of a 02 ,um filter and stored at - 70'C. This preparation was used for skin testing and for invitro stimulation. Sterile purified human alpha leucocyte IFN obtained from Interferon Sciences,Inc. (Brunswick, New Jersey, USA) was diluted in sterile PBS and stored at - 700C.

Target cells. Human K-562 cells were maintained as a continuous cell line in culture. Labellingwith 51Cr was performed as described previously (Brunner et al., 1968).

STA and IFN stimulation ofPBMNC. Peripheral blood was obtained in sterile vacutainer tubesusing EDTA as anticoagulant. Mononuclear cells (MNC) were isolated by means of Ficoll-Hypa-que gradient separations. After determining the viability by means of trypan blue exclusion, 1 x 106

cells were resuspended in 1-0 ml of culture medium which consisted of RPMI 1640 supplementedwith 5% heat-inactivated pooled human AB positive serum and 10 mm morpholinopropanesul-phonic acid (MOPS) in 12 x 75 mm clear round bottom plastic tubes. The cells were then culturedfor 5 days in medium alone, with Candida antigen at a concentration of 1:10, with PPD at aconcentration of 10 mg/ml or with IFN at a concentration of 1 x 103 units/ml at 370C in a humidifiedatmosphere containing 5% CO2 in air. Every culture run included cells from both normal subjectsand patients.

Assayfor CMC. Cytotoxicity was evaluated on day 0 for NK cell activity and on day 5 ofculturefor NK like CMC by resuspending the MNC population containing the effector cells in assaymedium (which consisted of RPMI 1640 supplemented with 5% heat-inactivated fetal calf serum(FCS) and 10 mm MOPS) making 1/3 dilutions of those cells, and adding 0 1 ml of each dilution totwo round microtitre wells. Each well then received 0-1 ml of assay medium containing 5 x 1035"Cr-labelled K-562 target cells. The microtitre plates were then centrifuged for 5 min at 200g andincubated for 4 h at 370C in a humidified atmosphere containing 5% CO2 in air. After this time theplates were centrifuged for 5 min at 400g and 0.1 ml of the supernatant fluid was removed forcounting in a well type scintillation counter (Nuclear Chicago-Searle, Des Plaines, Illinois, USA).Percentage cytotoxicity for each dilution was calculated from the formula:

ct/minexv. release ct/minsont. release X 100.

ct/minmax release- ct/minspont. release

Maximal release was determined by freezing and thawing of the target cells. Since the number ofcells each dilution contained was known, it was possible to construct dose-response curves. Byinterpolation from these curves, the percentage of cytolysis at a 10: 1 E: T (effector cell: target cell)ratio was determined. Every assay run included cells from both normal subjects and patients.

Skin testing. Skin testing with Candida antigen and PPD was performed by intradermalinjection of 0 1 ml of the concentrated Candida antigen preparation diluted 1:10 or of the PPDsolution diluted to contain 10 pg protein/ml. After 48 h the widest span oferythema and indurationin the area of skin testing was measured and recorded. In all cases, blood for isolation ofPBMNCwas obtained before skin testing was performed.

RESULTS

NK cell activityFresh PBMNC from normal subjects, patients with sarcoidosis, and pregnant women were assayedforNK cell activity. The mean values + standard error ofthe mean (s.e.) for each group are shown inTable 1. When the mean values for each group were compared to that obtained for the normal

Table 1. NK cell activity

Male Female

Normal 461 +4.3(8)* 307 + 23(15)Sarcoid 29-1(1) 22.7 + 3.8(9)*Pregnant 16-6+ 17(21)* 1st trimester 16 3+ 18(4)*

2nd trimester 17-4+3-3(9)*3rd trimester 15 9 + 2 4(8)*

NK cell activity was determined on day 0 using 51Cr-labelled K-562target cells in 4 h 51Cr release assays. The average percentage cytolysis at a10:1 E:T ratio for the subjects in each group is shown (±s.e.). Thenumber of subjects in each group is shown in parentheses. Asterisks (*)indicate mean values significantly different (P < 0 05 by Student's Mtest)from the mean value determined for the normal female group.

D. Tartof et al.504

NK cells in pregnancy and sarcoidosis 505women, definite differences were noted. NK cell activity was significantly higher in the normal menthan in the normal women (46 1 +4 3 vs 30 7 +2 3, P< 0005). In contrast, NK cell activity wasdecreased in the women with sarcoidosis compared to the normal women (22-7 + 3 8 Vs 30 7 + 2 3,P < 005) and even more decreased in the pregnant women compared to the normal women(166+17 vs 30-7+2-3, P<0005). The duration of pregnancy did not appear to affect thedepression in NK cell activity since patients in the 1st, 2nd and 3rd trimesters of pregnancy showedsimilar values (16-3 + 1[8, 17 4+ 3-3 and 15 9 + 2 4). NK cell activity in the single male patient withsarcoidosis was higher than the average value for the female subjects with sarcoidosis (29-1 vs22 7 + 3 8) but was much lower than the mean level determined for the normal male population(291 vs 46-1 +43).

STA and IFN stimulation ofNK like CMCThe PBMNC from the same subjects were exposed in vitro to Candida antigen, PPD and IFN for 5days after which time the level of NK like CMC in each culture was determined. Table 2 lists themean values obtained for each group of subjects. Once again, significant differences were found.

Table 2. Stimulation in vitro ofNK like CMC in human PBMNC

Stimulus Sex Normal Sarcoid Pregnant

Medium fMale 13 3+3 7(6)* 6 3(1)alone Female 5-2+ 14(13) 4 0+0 7(9) 3 7+0 8(20)

{ Male 53 0+8 1(6) 10 1(1)Candida ) Female 440+5-2(13) 176+45(9)* 258±43(20)*PPD fMale 55-2+8-2(6)* 4-7(1)Female 34-9± 56(13) 8 7 + 20(9)* 26- 1+ 51(20)

IFN{ Male 42.2+9 4(6)* 3-8(1)IFemale 16 2+3-1(13) 7-3+337(9)* 10 9+2-1(20)

NK like CMC was determined on day 5 using 51Cr-labelled K-562target cells in 4 h 51Cr release assays. The average percentagecytolysis at a 10:1 E: T ratio for the subjects in each group is shown(± s.e.). The number of subjects in each group is shown inparentheses. Asterisks (*) indicate mean value significantly different(P< 0 05 by Student's t-test) from the mean values determined in thenormal female group after each stimulus.

Candida antigen, PPD and IFN all stimulated higher levels ofcytolytic activity in the cells from thenormal men than in similar cells from the normal women. The differences did not however, reachstatistical significance in each case. There were statistically significant differences between the levelsofNK like CMC in the cells from the normal men compared to those in the normal women afterstimulation with PPD (552 + 8-2 vs 34-9 +5-6, P < 0-05) and IFN (42-2+ 9.4 vs 162 +3 1,P <001)but not after stimulation with Candida antigen (53-0 + 8 1 vs 44*0 + 5 2).

When similarly stimulated cells from the pregnant subjects were compared to those from thenormal women, the values in the pregnant group were consistently lower, however, only thedifference after stimulation with Candida antigen reached statistical significance (25 8+4 3 vs44-0+ 5 2, P< 0-01). On the other hand, STA and IFN stimulation of NK like CMC in the cellsfrom the women with sarcoidosis were uniformly and significantly depressed in comparison to thosein the cells from the normal women: Candida antigen (17-6 + 4-5 vs 44-0 + 5 2, P < 0-0025), PPD(87+20 vs 34-9+5-6, P<0001) and IFN (73+3-7 vs 16-2+3-1, P<0-05). (STA and IFNstimulations of NK like CMC in the cells from the single male patient with sarcoidosis weresimilarly depressed). Thus, both STA and IFN stimulation ofNK like CMC were more depressed inthe cells from patients with sarcoidosis than in those from pregnant subjects when both groups werecompared to similar stimulations in the cells from the normal women.

Comparison ofskin testing, STA and IFNstimulation ofNKlike CMCandNKcell activity in patientswith sarcoidosisAll 10 patients with sarcoidosis were skin tested with Candida antigen and PPD as described inMaterials and Methods. As control, eight normal volunteers (four women and four men) were skintested with Candida antigen alone. The mean values for erythema and induration are listed in Table3. Normal men and women showed no statistical difference in the skin test responses to Candidaantigen. The women with sarcoidosis developed significantly less erythema (23 1 + 3-4 vs 37 0 + 6 5mm, P<0 025) and induration (122+33 vs 24 5+3-7 mm, P<0 025) than the normal women.

Table 3. Skin test response to Candida antigen

Normal Sarcoid

Males { Erythema 500+±12-9(4) 18 0(1)Induration 27 0+5 8(4) 12 0(1)

Females f Erythema 37 0+6-5(4) 23-1+3-4(9)*FInduration 245 + 3-7(4) 12 2 + 3-3(9)*

Normal subjects and patients with sarcoidosis wereskin tested with Candida antigen. The extent of eryth-ema and induration present at the end of 48 h wasmeasured in mm's and the results shown are theaverages for each group + s.e. The number ofsubjects ineach group is shown in parentheses. Asterisks (*)indicate mean values significantly different (P < 0 05 byStudent's t-test) from the mean values determined forthe normal female group.

Correlation coefficients (r) were determined between ordered sets of the different responses inthe patients with sarcoidosis. Table 4 shows the results comparing the various in vitro and in vivoresponses in the 10 sarcoidosis patients. The skin test responses to Candida antigen in vivo and thestimulations ofNK like CMC by Candida antigen in vitro were significantly correlated. There wasalso a significant correlation between the in vivo responses to PPD and the in vitro stimulations ofNK like CMC by PPD. There was no correlation between the skin test response to Candida antigenand stimulation ofNK like CMC by PPD or between the skin test response to PPD and the amountofNK like CMC stimulated by Candida antigen. In addition, there were no correlations betweenNK cell activity and the in vivo or in vitro responses to either Candida or PPD or between the level ofNK cell activity and in vitro stimulation NK like CMC with IFN. On the other hand, the indurationdeveloped during skin testing with Candida antigen and the level ofNK like CMC stimulated byCandida antigen in vitro both correlated significantly with the level ofNK like CMC stimulated byIFN in vitro.

Correlations between NK cell activity and STA and IFN stimulation ofNK like CMC in pregnancySince we did not wish to skin test women during pregnancy, only in vitro responses were compared.The results of the correlations are shown in Table 5 where it can be seen that there was nocorrelation betweenNK cell activity in the cells from the pregnant patients and the response ofthosepatients' cells to STA or IFN stimulation of NK like CMC. There was, however, a significantcorrelation between stimulation ofNK like CMC by Candida antigen and stimulation ofNK likeCMC by IFN. No similar correlation existed between stimulation of NK like CMC by IFN andstimulation ofNK like CMC by PPD.

5o6 D. Tartof et al.

NK cells in pregnancy and sarcoidosis 507Table 4. Correlation coefficients between ordered sets of immune responses in 10 individual patients withsarcoidosis

Candidat PPDt IFNt NKT(CMC- (CMC- (CMC- (CMC-in vitro) in vitro) in vitro) in vitro)

Candida§(Induration-in vivo) 0.89* 0-44 064* 0 03

PPD§(Induration-in vivo) 0 47 064* 0-36 0 03

IFNt(CMC-in vitro) 0.76* 0-26 -0-14

NK(CMC-in vitro) -0-08 -0-06 -0-14

Correlation coefficients were determined between ordered sets ofindividual patient responses. For 10 patients a correlation coefficientof greater than 0-632 between two sets of data means there is greaterthan 95% probability that those responses are related. An asterisk (*)indicates those sets of data where a significant correlation (r> 0 632)exists.

t Sets listing the levels ofNK like CMC developed in the PBMNCfrom 10 sarcoidosis patients after 5 days of exposure in vitro to theagent shown. Cytolysis was determined at a 10: 1 E:T ratio.

$ Set listing the levels of NK cell activity found on day 0 inPBMNC from the same ordered group of 10 sarcoidosis patients.Cytolysis was determined at a 10:1 E: T ratio.

§ Set listing the levels of induration present at 48 h in the skin testresponses to the agent shown in the same ordered group of 10sarcoidosis patients. Induration was measured in mm's.

Table 5. Correlation coefficients between ordered sets of immune responses in 20 pregnant women

Candidat PPDt IFNt(CMC- (CMC- (CMCin vitro) in vitro) in vitro)

NKt(CMC-in vitro) -0-03 0 01 0-23

IFNt(CMC-in vitro) 0.51* 0-38

Correlation coefficients were determined betweenordered sets of individual patient responses. For 20patients a correlation coefficient of greater than 0-444between two sets ofdata means there is greater than a95% chance that those responses are related. Anasterisk (*) indicates those sets of data where asignificant correlation (r > 0-444) exists.

t Sets listing the levels ofNK like CMC developedin the PBMNC from 20 pregnant patients after 5 daysof exposure in vitro to the agent shown. Cytolysis wasdetermined at a 10: 1 E:T ratio.

I Set listing the levels ofNK cell activity found onday 0 in PBMNC from the same ordered group of 20pregnant patients. Cytolysis was determined at a 10: 1E: T ratio.

D. Tartof et al.

DISCUSSION

Several observations made during the course of the study warrant discussion. The first was thatalthough NK cell activity was higher in normal men than in normal women, it was even lower inpregnant women and in women with sarcoidosis. NK cell activity was most reduced in the pregnantwomen. When STA and IFN stimulations of NK like CMC in vitro were evaluated it was againnoted that the levels were decreased in the women with sarcoidosis and in the pregnant womenrelative to the normal women, however, in this case the values were much more depressed in thewomen with sarcoidosis than in the pregnant women. Thus different factors appeared to beresponsible for the depression in these responses in the two conditions.

It is well known that the DTH response to STA stimulation is decreased in patients withsarcoidosis (Friou, 1952; Sones & Israel, 1954; James, 1966). The exact mechanism of this decreaseis unknown. We have previously shown that in normal individuals there is a good correlationbetween the magnitude of the skin test response to Candida antigen in vivo and Candida antigenstimulation of NK like CMC in PBMNC in vitro (Tartof et al., 1980). We also reported that STAstimulation of NK like CMC was decreased in PBMNC from patients with systemic lupuserythematosus (SLE) and that the magnitude of the decrease was related to disease activity (Tartofet al., 1982). Other observers had previously shown that the DTH response to STA stimulation wasdecreased in SLE. That decrease was also related to disease activity (Hahn, Bagby & Osterland,1973; Horowitz & Cousar, 1975; Rosenthal & Franklin, 1975). Recently, utilizing artificiallyinduced skin blisters to obtain cells from human DTH responses we observed that blistersassociated with positive DTH responses contained mononuclear cells capable of mediating NK likeCMC against both NK sensitive and NK resistant target cells (Tartof et al., 1983b). On the basis ofthese findings we have proposed that locally activated NK like killer cells may be effector cells in thehuman DTH response. The findings in the present study are consistent with this hypothesis.Although the in vivo and in vitro responses to STA stimulation were abnormal in the patients withsarcoidosis, there was a significant correlation between the stimulation ofNK like CMC by a givenskin test, in vitro, and the magnitude of the skin test response to that same antigen in vivo in thosepatients. Thus, depression of STA stimulation ofNK like CMC might help explain, at the cellularlevel, why anergy occurs in sarcoidosis.

We termed the skin test antigen stimulated killer cell the STAK cell (Tartof et al., 1980) anddemonstrated that similar to the NK cell (Zarling & Kung, 1980) the STAK cell is OKMl positiveand OKT3 negative (Tartof et al., 1983a). Since different antigens stimulated the same NK likekilling, we hypothesized that the STAK cells were secondarily stimulated by antigenically specificcells within the MNC population (Tartof et al., 1980). Previous investigators demonstrated thatIFN directly stimulates cells that mediate both NK and NK like killing (Santoli, Trinchieri &Koprowski, 1978; Gidlund et al., 1978; Herberman, Ortaldo & Bonnard, 1979; Targan & Dorry,1980). It may not be surprising therefore that indirect Candida antigen stimulation ofNK like CMCcorrelated so well in this study with presumed direct stimulation of the STAK cell subpopulationwith IFN since Candida antigen is virtually a universal stimulus. In this study and in our previousstudies (Tartof et al., 1980, 1982) we found that the vast majority of normal subjects responded invivo and in vitro to stimulation with Candida antigen. The fact that both direct IFN and indirectCandida antigen stimulation ofNK like CMC were depressed in the same patients implies that thedefect in sarcoidosis may primarily lie in the killer cell population and not in the antigen specific cellsthat may secondarily stimulate the killer cells. Experiments are underway to explore these vitalissues.

Although cell-mediated immunity must be altered in some manner during pregnancy to preventdestruction of the fetus which bears 'foreign' paternal histocompatability antigens on its cellsurfaces, most cell-mediated immune responses have not been shown to be severely or consistentlydecreased during pregnancy (Lichtenstein, 1972; Peer, 1958; Lewis et al., 1966; Cepellini et al., 1971;Carr, Stites & Fudenberg, 1974; Daunter, Knoo & Mackay, 1979; Rocklin, Kitzmiller & Kaye,1979; Skinnider & Laxdal, 1981). Our results which are similar to those reported previously byothers (Baines, Pross & Millar, 1978) show thatNK cell activity is very depressed during pregnancy.

5o8

NK cells in pregnancy and sarcoidosis 509Recently various groups have shown that NK cells may be involved in the immune destruction ofcells perceived as 'non-self since NK cell activity was noted to be markedly increased duringtransplant rejection (Lipinski et al., 1980; Clark et al., 1980; Guillou et al., 1982; Ono et al., 1982)and graft versus host disease (Lopez et al., 1979; Dokhelar et al., 1981). Thus, inhibition of thisactivity during pregnancy may be a useful adaptation to help ensure fetal survival. The relativedecrease in NK cell activity in normal women may set the stage for this even greater decrease thatoccurs during pregnancy. These findings suggest that NK cell activity may be influenced by factors,such as female hormones, that are altered during pregnancy. Previous investigators have shown inanimal studies that estrogen inhibits NK cell activity (Kalland & Forsberg, 1981). We are pursuingstudies to determine what factors in pregnancy are responsible for maintaining low NK cell activityand how low NK cell activity may relate to fetal survival.

Our findings demonstrate that there are definite defects in NK cell activity and STA stimulationofNK like CMC in pregnancy and sarcoidosis. These processes were affected to different degreeswith the greatest decrease in NK cell activity occuring in pregnancy and the greatest decrease in STAstimulation ofNK like CMC occurring in sarcoidosis. There was no correlation between NK cellactivity and any of the other responses in the pregnant women or the patients with sarcoidosis.Thus, NK cell activity cannot be relied on to indicate the status ofthe cell-mediated immune systemin a given individual.

We would like to thank Mr David Michel and Mr Mitchel Kim for their expert secretarial assistance in thepreparation of this manuscript. This work was supported by grants from the Illinois Chapter of the ArthritisFoundation, and The Chicago Community Trust.

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